The co-owner of a crane company where the suspect in a shooting at a US restaurant once worked said she urged federal officials to keep him in custody after he was arrested at the White House last year.
Travis Reinking, 29, is accused of opening fire outside a Waffle House with an AR-15 rifle and then storming the restaurant in Nashville, wearing only a green jacket.
Four people were killed and four wounded in the shooting.
Reinking had exhibited erratic behaviour for years before the shooting, and Darlene Sustrich, who co-owns a Colorado crane company where Reinking once worked, said they got a call from the FBI after he allegedly tried to jump the White House fence last July.
"We told them, 'Hang on to him if you can. Help him if you can'," Ms Sustrich said.
Reinking has been charged with four counts of criminal homicide, and Metro Nashville Police Department said he also faces four counts of attempted murder and one count of unlawful possession in the commission of a violent felony.
Davidson County Sheriff Daron Hall said Reinking has been "compliant" and "co-operative" since he was transferred to the jail late on Monday after he was captured near the apartment where he lived.
Reinking is wearing a vest known informally as a "suicide smock" and will remain under close observation at a maximum-security facility in Nashville.
Meanwhile, the man who snatched the rifle away from Reinking during the shooting told Tennessee lawmakers on Tuesday he faced "the true test of a man", drawing a standing ovation during his brief address.
As the state House hailed him as a hero, James Shaw Jr said he acted to save his own life and saved others in the process.
"I never thought I'd be in a room with all the eyes on me, but you know, I'm very grateful to be here," he told House members.
Mr Shaw said he has been to see some of the shooting victims in hospital and they all remembered him. He apologised to the people whose loved ones died in the attack.
The state Senate also honoured Mr Shaw on Tuesday.
After the shooting, authorities say Reinking escaped on foot from the restaurant and shed his only item of clothing.
By the time he was captured in the woods nearby, police had searched his apartment and found the key fob to a stolen BMW they had recovered in the car park days earlier. The BMW theft had not initially been tied to Reinking.
Police seized multiple items from his apartment including a Remington rifle with a magazine, cartridges for different calibres of gun, two rifle scopes and gun cleaning equipment.
Nashville Police Department Lieutenant Carlos Lara told reporters Reinking was arrested on Monday after detectives were tipped to the suspect's presence by construction workers. He was carrying a black backpack with a silver semi-automatic weapon and .45-calibre ammunition.
The arrest ended a 24-hour manhunt involving more than 160 law enforcement officers, but it left troubling unanswered questions about official responses to months of bizarre behaviour before the restaurant attack, including encounters with police in Illinois and Colorado and an arrest at the White House that raised red flags.
Sustrich, Reinking's former boss, described him as appearing paranoid and delusional at times. A former co-worker told a police detective Reinking was infatuated with singer Taylor Swift and claimed to be a sovereign citizen.