Gardaí say that investigations into six killings that took place in Cork since July are progressing well.
A woman, 37, was the third person arrested in relation to the murder of Timmy Hourihane, 53.
The former chef, who was homeless at the time of his death, was fatally assaulted and left outside his burning tent in Cork city centre on October 13.
The woman was released without charge on Wednesday night and gardaí are preparing a file for the Director of Public Prosecutions (DPP).
Two other males have been questioned under arrest in relation to the father-of-one's violent death.
A man, 26, from Mayfield was first arrested by detectives and another man, 37, was later arrested in the Midlands. Both men were released without charge and gardaí are preparing files for the DPP.
Gardaí recently travelled to Romania where they questioned a person of interest in relation to the brutal killing of Frankie Dunne whose dismembered body was found in the grounds of a vacant house on Boreenmanna Road on December 28.
Gardaí have also spoken to a number of other people in relation to the father-of-three's death.
A teenager has been charged with murder following the fatal stabbing of engineering student Cameron Blair, who was attacked at a house party on the Bandon Rd in Cork city last month.
The juvenile has been remanded in Oberstown detention centre where he is to be psychologically assessed.
A man, 46, has been arrested and a file is being prepared for the DPP following the death last October of James Duncan. Mr Duncan, 40, was seriously assaulted while attending a soup kitchen in Patrick St on September 12. He suffered traumatic brain injuries in the assault and died one month later in the Intensive Care Unit at Cork University Hospital.
Two people have been charged in relation to the death of Paul Jones, 55. Mr Jones sustained a violent assault in which he was stabbed a number of times and received a serious injury to his head. He was found dead in his home on Bandon Rd in September.
His sister, Helen Jones, and Keith O’Hara who lived with Ms Jones, were charged with trespass-related charges. A file on the case was sent to the DPP on December 10.
A woman has also been charged with murder following the death of toddler Santina Cawley. Santina died on July 5 after she was rushed to hospital with serious injuries from an apartment on Boreenmanna Rd.