'Learned impunity' - How years of psychiatric illness led to the shooting dead of Garda Horkan

Stephen Silver had fired one shot for each of his involuntary admissions to psychiatric hospitals over the past 26 years

The court heard some of Stephen Silver’s involuntary admissions to hospital involved threats and aggression towards gardaí and on occasion violence towards hospital staff. File picture: Colin Keegan, Collins Dublin

Stephen Silver had a “seething resentment” toward gardaí and when opportunity presented itself he grabbed it, literally, with both hands, shooting Garda Colm Horkan 11 times with his own gun as the officer lay helpless on the ground.

Silver had fired one shot for each of his involuntary admissions to psychiatric hospitals over the past 26 years.

The jury heard expert testimony that Silver's “learned impunity” meant he expected to be treated as he always was when he incited an aggressive confrontation with gardaí; the situation would be diffused, he would be brought to hospital where he would remain for a period before his release and resumption of normal life. 

However, instead of resuming his life, Silver will now serve a minimum sentence of 40 years in prison for capital murder, after a Central Criminal Court jury rejected his defence that he was suffering a relapse of his bipolar disorder that diminished his responsibility at the time of the shooting.

Taking to the stand at his own trial, Silver had given a vivid description of the attack, telling the jury that he pulled the trigger and kept firing “until there was no ammunition left”.

Garda Helen Gillen, who became emotional as she described in court how she witnessed the murder of her colleague firsthand, said that after Garda Horkan fell, Silver had walked over “with purpose” and repeatedly fired down into the officer.

Unarmed and, despite the pleas of her colleague to maintain a distance, Gda Gillen confronted and handcuffed Silver. “I was trying to save the guards."

Truculent, disgruntled and aggressive, 46-year-old motorbike mechanic Silver demonstrated his disdain for the force several times in the hours before he shot and killed Garda Horkan, stopping at Castlerea Garda Station in Co. Roscommon on the afternoon of June 17, 2020, to deliver an “angry rant”. 

Later that day he drove a motorcycle dangerously around the usually quiet suburban Knockroe estate and began shouting in the street, daring the "armed squad" to come down and “take a shot”.

Detective Garda Colm Horkan, a trusted member of the force, had 25 years experience and was well regarded by his colleagues.

Such behaviour was a deliberate act to attract the attention of the gardaí, prosecution lawyers contended during the trial. And attract garda attention it did; numerous concerned local residents contacted Castlerea Garda Station about the disturbance.

Garda Horkan, a single man who lived with his father in Charlestown, Co. Mayo, was on duty that night in plain clothes and an unmarked Hyundai garda car. A trusted member of the force, the garda had 25 years experience and was well regarded by his colleagues. Gda Horkan was trained in the use of firearms and had been asked to fulfil detective duties during the pandemic. 

After driving round the Knockroe estate and finding calm had returned, the acting detective — oblivious to the fact he was about to be killed with his own weapon — encountered Silver and James Coyne as he made his way back through the town.

Silver and Mr Coyne were old friends but the pair hadn’t seen each other in over a decade. However, after watching a video of a garda raid at his friend's house, Silver believed an injustice had been carried out and he laid the blame squarely at the feet of the guards.

'I was trying to save the guards'

Mr Coyne told the trial he hadn’t seen Silver in a long time but when the bike mechanic called to his house they got talking and Silver asked Mr Coyne to go with him to his bike shop in Foxford. At the workshop, Silver gifted one of his expensive motorbikes, a 750cc Kawasaki Ninja, to Mr Coyne. "You're a natural, you can have it," Silver had told Coyne.

The two men returned to Mr Coyne’s house in Knockroe where they drove the bike without lights or helmets, noisily and at speed around the estate. After his trip around the green, Silver did a “burnout” with the back wheel of the bike before daring “the armed squad to come down and to have a sniper to get a good shot”.

So het up was he that by the time the pair began their journey to Castlerea for a pizza, Mr Coyne made a concerted effort to steer Silver in a different direction and away from Castlerea Garda Station.

“I decided to go the new road to avoid trouble,” Mr Coyne told the trial. 

I was trying to save the guards.  I had a feeling if we went by the garda station again, he was going to go in again. I was trying to protect the guards.

Mr Coyne told the trial that when Garda Horkan pulled up alongside them, the passenger window was down. Silver put his head in the window and said something before the garda got out of the car. He said Garda Horkan, whom he knew, said hello to him before telling Silver “you’re under arrest”.

Mr Coyne said the incident then “turned into a fight” between Gda Horkan and Silver and the next thing he remembered was the guard “going down”. “There was no shelter and the gun was going off. I thought I heard four or five shots."

Just minutes before midnight, what should have been a straightforward arrest became a struggle for life in the instant Stephen Silver felt the gun on Garda Horkan’s hip.

Stephen Silver told the trial that his hostility to gardaí got worse as his interviews with detectives at Castlerea Garda Station went on and that by the final interview he was “extremely hostile to gardaí”. File picture: Colin Keegan, Collins Dublin

Silver said the two men grappled for control of the gun but he ultimately won the struggle and proceeded to beat the garda with the butt of the gun before rolling away, grasping the firearm with both hands and shooting the garda as he lay defenceless on the ground.

Mr Coyne, who had watched on, stunned by what unfolded in front of him, told the jury: “I just stood there. Stupid. He could have killed me.” Silver’s anger and aggression on the day of the killing was never in any doubt. Neither was the accused’s responsibility, as he had pleaded guilty to manslaughter and admitted shooting and killing Gda Horkan.

“The main issue is Mr Silver’s state of mind at the time,” defence counsel Dominic McGinn SC told the trial.

What jurors were asked to determine over the six week-long trial was whether the anger and hostility shown by Silver was the result of a specific resentment and querulousness towards gardaí or whether it was a sign of a relapse of his bipolar affective disorder.

Learned impunity 

Dr Brenda Wright, interim clinical director at the Central Mental Hospital, said that as a consequence of his mental illness, Mr Silver’s capacity was “significantly impaired” at the time of the shooting.

The psychiatrist acknowledged that Silver was at times “facetious, contemptuous and hostile” towards detectives during interview but said his “grossly inappropriate behaviour” on these occasions was indicative of mental illness.

She said his judgment was impaired at the time of Garda Horkan’s killing and contributed significantly to his actions at the time.

Stephen Silver's sister, Marian Bruen, said there were numerous “red flags” during the call with her brother the day before the shooting. File picture: Collins Courts

Silver’s sister, Marian Bruen, told the jury that she knew her brother was "very unwell" the day before the shooting and that her family planned to have him admitted to a psychiatric hospital. She said she “knew immediately” Mr Silver wasn’t himself during a phone call on June 16, 2020, and said there were numerous “red flags” during the call.

However, Professor Harry Kennedy took a different view and said he found “no positive evidence” that Silver had suffered a relapse of bipolar affective disorder at the time the garda was shot and killed. Professor Kennedy said the accused appeared to show “poor social judgement” and engaged in “self-dramatising behaviour”.

Silver's “learned impunity” meant he expected to be treated as he always was when he incited an aggressive confrontation with gardaí; the situation would be diffused, he would be brought to hospital where he would remain for a period before his release and resumption of normal life.

It was a cycle which had evolved over more than 20 years and countless psychiatric admissions, both voluntary and involuntary.

The court heard that Silver first showed signs of illness in 1997 at the age of 22 and had 16 admissions to hospital between 1997 and 2010, 11 of which were involuntary. There were two further hospital admissions in 2018 and 2019, both of which were voluntary.

In his evidence, Silver said that during his first episode, he was experiencing fleeting thoughts and did not sleep for seven days, which caused him to become sleep deprived. He told the trial he was hospitalised in Roscommon Hospital and was brought there by the guards.

The court heard that Stephen Silver often failed to attend outpatient appointments following his release from hospital and frequently stopped taking his medication, sometimes within days of discharge.

It was the first of many encounters he would have with gardaí over the years. The court heard some of Silver’s involuntary admissions involved threats and aggression towards gardaí and on occasion violence towards hospital staff.

During a mental health episode in 2006, gardaí attended to escort Silver to hospital. He went to his bedroom to get changed but emerged carrying a long sword and acting in a threatening manner to gardaí. He eventually put the sword down and allowed the guards to handcuff him, going on to have tea with them back at the garda station. In his direct evidence to the court, Silver denied he had been threatening towards gardaí and described the sword as “an ornament” which had been hanging on the wall.

Professor Kennedy said this incident was just one of a number of examples of Silver’s self-dramatising behaviour. The court that Silver often failed to attend outpatient appointments following his release from hospital and frequently stopped taking his medication, sometimes within days of discharge.

He had a long period without any incident or illness before he was admitted following a relapse in 2018 when he tested positive for PCP, a powerful mind-altering hallucinogenic, following a bike trip to Germany. Silver denied taking the drug and told the court he must have been “spiked” on the trip. 

His final admission was in 2019, nine months before the shooting when he was admitted voluntarily and stayed for several weeks. The court heard that following his discharge he again stopped taking his medication. He was still off his medication when he shot and killed Garda Horkan shortly before midnight on June 17.

'You killed a garda'

In his evidence, Silver said he thought the garda was “a heavy down from Dublin” who was trying to kill him. He told the trial: “There was one man in the car staring at me. He stopped and asked me who I was, and I said, ‘Who are you?’ and he said, ‘What’s your name?’ I said my name and he said, ‘I’m a guard.’ 

"I didn’t believe he was a guard, he didn’t come across as one. He was wearing a Hilfiger jacket. It didn’t look like a jacket worn by a guard. I wondered what he wanted. He was right up to me, very close to me, and I said, ‘Stand back’.” 

He said that he and Gda Horkan struggled for a bit before Mr Coyne grabbed Mr Silver from behind and tugged at him.

“I fell to the ground on one knee. I was in the process of getting up and had my hand on his hip, and I felt the gun. I thought, ‘Oh shit, I’m going to be shot here.’ I pulled my hand away, and I put my hand on the gun getting up.” He said the pair then “wrestled” before the gun came out.

Silver said he pulled the trigger and there was a “loud pop noise”. He said both his and Gda Horkan’s hands were on the gun at the same time before the garda started falling backwards and he hit him on the head with the butt of the gun.

Silver said:

I started firing the gun at him. I was just afraid, full of adrenaline. I felt he was trying to kill me. I still thought he was an assailant. I kept shooting until the gun finished and there was no ammunition left. It happened so quickly.

He said that the gardaí then arrived and he threw the gun away.

Garda Helen Gillen said that she and her colleague Garda Aidan Fallon had been in a patrol car when she noticed two people “grappling” at the junction of Main Street and Patrick Street in Castlerea. She then heard what she thought was a number of shots before seeing a man “stagger back” and fall down.

Gda Fallon immediately moved the car to block the road and as Gda Gillen looked back, she said a second man came walking over “with purpose” and “shot the person on the ground a number of times.” She said she heard Garda Fallon say: "He’s killed a man, He’s killed a man”.

“Then I got out of the car. Aidan was shouting at me to come back but I walked up the road.” The garda said she remembered the man looking up and heard something being thrown away, only realising afterwards that it was the gun.

She said Gda Fallon then “pulled over the man” and “that’s when Aidan had said it was Colm that was shot” and noticed the empty holster on the left side of his trousers. “Aidan said: ‘You shot him, you shot him. You killed a garda’.

She said the man then said no, it was his [Garda Horkan’s] gun and he added “with all that’s going on in the world with the police”. 

The garda said she thought she could feel a slight pulse and started CPR while they waited for back-up to arrive.

Garda Aidan Fallon said he heard a number of shots and saw one man lying on the ground with the other man on his knees with his hands out shouting: “I shot him, he’s dead”. File picture: Collins Courts

In his evidence, Gda Fallon told the court he saw a man lying in the middle of the road and the other man standing over him with a gun. The garda said he heard a number of shots and saw one man lying on the ground with the other man on his knees with his hands out shouting: “I shot him, he’s dead”.

Gda Fallon said he went to the victim on the ground and pulled him over onto his back to start CPR. He said he saw then that it was Gda Horkan on the ground.

“His eyes were still open but the life had gone out of them, and I instantly thought the worst,” he added. He said he performed CPR on Gda Horkan while Gda Gillen handcuffed Silver. As he tried to save his colleague’s life, Silver told him he was “doing it wrong”.

“I saw a smirk on his face. He wasn't saying it in a helpful way, he was trying to antagonise me,” said Gda Fallon.

The garda said that he asked the man to sit down and he refused. He gave evidence that the man said: “I know what they did to that black man in America”. He also referenced the Black Lives Matter protest movement.

Gda Fallon said he told the man that he had shot a detective, and the man said: “Of course I shot him, he had a gun. What kind of a detective wears a red Tommy Hilfiger jacket? He doesn’t look like a good detective now.” 

In her evidence to the trial, State Pathologist Dr Linda Mulligan said that Garda Horkan sustained multiple gunshot wounds to his left shoulder, neck, abdomen, armpit, chest, hip and both his left and right thigh. She said the garda appeared to have been shot 11 times and that the injuries sustained were catastrophic and non-survivable.

Extremely hostile 

Dr Greg Kelly, a Castlerea-based GP who saw Silver in the garda station shortly after he was arrested, said the mechanic told him his mental health began to decline when covid restrictions were in place and that covid had “destroyed everything”.

He said the day after the shooting the accused appeared “elated” and “did not appear to have taken on the gravity of the situation”.

Silver told Dr Kelly that he was living in a shed in Foxford and that covid had “upset his whole life”. Silver also said he had “shot a garda in self-defence" and “his mood and demeanour seemed wholly inappropriate for the situation he was in,” the doctor added.

The doctor said the accused appeared “agitated” when he first spoke to him through a hatch door in the early hours of June 18, 2020. but said Silver was also “lucid” and “coherent”.

Silver requested Valium but the doctor did not have any and instead gave him 50mg of Seroquel, an antipsychotic drug. Dr Kelly said Silver requested a glass of water and then asked for a second one “because he thought the first one was poisoned”. The doctor said the fact Silver believed the first glass of water he had been given was poisoned suggested “a high state of delusion”.

Dr Kelly said he spoke to Silver again at 3pm on June 18 and found him less agitated and distressed. The doctor spoke to Silver at lunchtime the following day and told gardaí that the accused was fit to be interviewed. “He told me ‘I’ll be out of here this evening’”, Dr Kelly said, adding he felt it was an “extraordinary attitude to have”.

The jury also heard evidence from Consultant Psychiatrist Dr William Monteiro, who said Silver refused a psychiatric assessment on the night he was arrested. Dr Monteiro said that Silver showed “no evidence of an active mental illness” when he assessed him and displayed “a large measure of control”.

Stephen Silver first showed signs of illness in 1997 at the age of 22 and had 16 admissions to hospital between 1997 and 2010, 11 of which were involuntary. File picture: Colin Keegan, Collins Dublin

The psychiatrist said he interacted with the accused twice over a short period, during which time Silver “refused to have very much to do with me”.

“The guard explained who I was and why I wanted to see him. He said ‘well I don’t know this man I don’t want to talk to him’. He was clearly switching me off so to speak and focusing on the guard.” 

Dr Monteiro said he observed the defendant and his interactions with the guard for some time and noted that the accused was “clear” and “lucid” and “he could engage in normal conversation”. “I thought there was no evidence of an active mental illness. That didn’t mean he doesn’t have one,” Dr Monteiro added.

He said his main concern was if he had enough data to conclude Silver was fit to be interviewed.

The court heard evidence that in the time leading up to the shooting, while Silver was staying in Dublin, he had “fleeting thoughts” that an Australian woman he was with was in MI6.

While under cross-examination from Michael Delaney SC, prosecuting, Silver denied “inventing” that he believed the woman was in MI6 in order to “bolster his case” insisting: “No, I had these thoughts”.

Silver agreed with Mr Delaney that his hostility to gardaí got worse as his interviews with detectives at Castlerea Garda Station went on and that by the final interview he was “extremely hostile to gardaí”.

However, when Mr Delaney put it to him that there was a “particular reason” for this, that “you expected that you would be released at that stage”, Silver denied this was the case.

Mr Delaney said Silver’s previous criminal behaviour had never resulted in a prosecution and instead would end with him being admitted to hospital. He put it to the accused that he believed this was what would happen on this occasion also but Silver said this wasn’t the case.

'Accept it and move on'

During the trial, the jury viewed footage from five garda interviews that were carried out over the course of two days following Silver’s arrest.

In one interview, Silver claimed he had been “set up” and told the interviewing officers: "One of your guys died. Accept it and move on.” He also told the detectives: "This is the easiest police situation I've been in. And I've shot a man. I've had worse things walking down the street.” 

At one point Silver claimed Garda Horkan had “shot himself accidentally” because he was “an idiot with a firearm”. The accused also told gardaí: “Prick. Now he’s dead and I’m alive and you’re making a huge f**king deal about it.” 

On his second day of interview, Silver’s behaviour was becoming more erratic and at various times he refused to answer questions, whistled, sang, faced into the corner and at one point claimed he was a Captain of the 62nd Cavalry Reserve with the Connaught Rangers.

The accused told the detectives he had defended himself against “an armed assailant”.

If that’s my crime, that's my crime. I defended myself against an armed assailant on my way to Apache Pizza.

During the interviews, it emerged that Silver had met Gda Horkan almost 20 years before he shot the garda dead. Detectives told Silver that Gda Horkan had attended at his house in 2003 at the request of his family and had escorted him to a psychiatric hospital.

Asked if he had ever met Garda Horkan before, Silver can be heard on the video singing “We Have All The Time In The World” and making reference to “Detective Garda Henry Hippo and Paddy Farrell”. When asked if he remembered the meeting, Silver replied: “I do in my hole."

When told that Garda Horkan was there [in 2003] to escort him to Roscommon General Hospital, Silver said: “Do you know how many guards have escorted me in my lifetime?” He then added: “A little dirt bag like that got shot with his own f**king gun” before stating “all I did was disarm him”.

Silver went on to refer to Garda Horkan as a “pr**k” before adding: “He wouldn’t be f**king dead now, would he, if he’d stayed in the car... I warned ye. Day in day out, same sh*te. I’ve better things to be doing.” However, Silver remained silent when Detective Inspector Brian Hanley asked why he didn’t walk away when he got possession of the gun.

“Why are we having a State funeral for Colm Horkan when he should be home with his family, and you should be home with your family but you’re not. You’re here as a result of your actions and Colm Horkan is dead as a result of your actions.” 

A manic relapse 

During the trial, Silver’s state of mind at the time of the shooting was the main issue of contention, with expert medical witnesses disagreeing fundamentally on whether or not the accused was suffering a relapse of his bipolar affective disorder when he pulled the trigger.

Dr Wright said the grandiose ideas displayed by Silver and his disinhibited behaviour, including taking his shoes off and massaging his feet whilst being interviewed, showed he was incongruous to the situation he found himself in.

The psychiatrist told the trial that Silver’s behaviour during garda interviews became erratic and “increasingly bizarre” and in her view was consistent with previous relapses of his bipolar disorder.

Outlining the findings of her report, Dr Wright said in her professional opinion, Silver’s illness at the time of the killing of Garda Horkan was such that it impaired his thinking and his judgment and therefore contributed significantly to his actions at that time.

The psychiatrist said it was her view that at the time of the offence Silver was mentally unwell, secondary to non-compliance with medication, and was experiencing a manic relapse of his condition.

Consultant forensic Psychiatrist, Dr Brenda Wright, said Stephen Silver's judgment was impaired at the time of Garda Horkan’s killing and contributed significantly to his actions at the time. File picture: Collins Courts

Dr Wright said Silver’s belief that his female companion was in MI6 and the fact he had given away his motorcycle to James Coyne though he could not afford to do this was further evidence of a relapse of his mental illness.

Dr Wright noted that later in the interview Silver began wiping his nose vigorously, told his solicitor “I’ve blood in my snout” and laughed when gardaí mentioned he previously met Garda Horkan.

He then claimed he was “f**king off for a pint” and added “the cavalry will take care of you”. The accused then sat down and picked his nose before putting some of the tissue he had been using into his mouth and chewing it.

Dr Wright said Silver’s behaviour during this whole sequence was “grossly inappropriate” and he appeared “not to appreciate the gravity of his circumstances”.

The psychiatrist said:

It's my view that he is mentally unwell during those interviews.

She added there is an escalation of this in the fifth interview over and above the others.

However, Professor Kennedy said Silver had a long history of behaving in a “disruptive manner”, requiring his family and members of the public to seek the assistance of the gardaí.

He said Silver had learned from experience that he would not be charged and his surprise at being detained following the fatal shooting of Garda Colm Horkan was understandable because of his “learned impunity”.

Prof. Kennedy said that during garda interviews, Silver showed a “strength of will” and was “not suggestible”. The mechanic appeared to show “poor social judgement” and engaged in “self-dramatising behaviour”, the psychiatrist said.

All of this could be explained by Silver’s personality, Prof. Kennedy contended, heightened under the conditions of the stress and strain of his arrest and the behaviours were not the result of his mental illness.

A seething resentment 

In his closing speech, Mr Delaney said Silver had a "seething resentment" toward gardaí and the shooting of Garda Colm Horkan was “a deliberate action done with the intent of murder".

He said Silver had an “overarching tendency” to tell “self-serving accounts” and said the jury could not rely on what the accused had said in interview or told psychiatrists because "whether he is well or unwell, he has a tendency to embellish things or to tell outright lies”.

“He denied itching for a confrontation with the gardaí, but we suggest the evidence suggests the opposite,” said Mr Delaney. “He had a seething resentment towards the gardaí, something that was reflected in his interview where he said: ‘I have a sh**load of complaints against the gardaí, a list as long as my arm’.” 

Counsel said that remarks made by Silver in his interviews with gardaí about being set up and claiming Gda Horkan had killed himself were all part of “a defensive strategy to cast himself as the innocent party”.

In his closing address to the jury, Mr McGinn said the shooting of Garda Horkan was “not a rational act” and said the very act of shooting Garda Colm Horkan should “raise questions” about Stephen Silver’s mental capacity. Mr McGinn described Garda Horkan’s death as a “terrible tragedy” that “should not have happened”.

He said Silver did not display a lot of “intact social functioning” on the day of the killing and pointed to the manner in which the accused behaved and spoke to gardaí in the garda station, his shouting in the street and pacing up and down.

He told the jury Silver’s behaviour while in custody was “erratic”, and included urinating in his cell, banging his head off a wall and pacing around. Counsel said shooting Garda Horkan was not a “targeted" or deliberate attack on a garda. It was instead, he contended, a chance encounter.

“There’s apparently no rational basis or motivation for what happened so the very act of shooting Garda Horkan should raise questions about his mental capacity because it doesn’t make sense,’ he said.

Mr McGinn said the natural conclusion was that Silver was in a relapse of his bipolar affective disorder at the time.