Eddie Ray Routh was crying, shirtless, shoeless and smelling of alcohol when police caught up with him walking the streets of his hometown of Lancaster, Texas.

His family didn't understand what he -- a Marine veteran suffering from post-traumatic stress disorder -- was going through, he told the officer last September 2, according to a police report.

He had a simple message that was as much a plea as it was a complaint: I'm hurting.

That visit -- which came after Routh, angry that his father was going to sell his gun, left the house and threatened, his mother told police, to "blow his brains out" -- prompted him to be placed in protective custody and sent to Dallas' Green Oaks Hospital for a mental evaluation.

Six months later, the 25-year-old Routh is in custody once again -- this time in a central Texas jail, facing murder charges in the deaths of America's self-proclaimed most deadly military sniper ever as well as another military veteran.

He is on a suicide watch and under 24-hour camera surveillance, Erath County Sheriff Tommy Bryant said Monday.

And he's already run into further trouble, becoming aggressive with guards in his cell after refusing to give up a spork and dinner tray Sunday night, according to the sheriff.

So who is Eddie Ray Routh?

Bryant has said Routh was in the Marines for four years, though it is unclear how much of that time, if any, was in combat zones. Shay Isham, a lawyer appointed by a judge Monday morning to represent Routh, said his client spent roughly the last two years in and out in Veteran Affairs medical facilities for treatment of mental issues.

His personal history and psychological make-up has come under the spotlight after the bloodshed Saturday.

It was then, officials say, Routh killed his two fellow veterans on a gun range located in a remote part of the Rough Creek Lodge and Resort's vast 11,000 acres.

This was, Bryant said, after Routh's mother "may have reached out to" one of the victims -- Chris Kyle, author of the best-selling book "American Sniper" -- "to try and help her son."

The suspect was "a troubled veteran whom they were trying to help," said Craft International, a company founded by Kyle, who since retiring from the Navy in 2009 had sought to assist ex-troops with PTSD.

Why might Routh have killed these men? He "is the only one that knows," Erath County Sheriff's Capt. Jason Upshaw told reporters on Sunday.

"I don't know that we'll ever know," Upshaw said.

Victims hailed as dedicated, caring patriots

No one else saw the shooting of Kyle and his friend, Chad Littlefield, according to Upshaw.

It occurred sometime after 3:15 p.m. (4:15 p.m. ET) Saturday, when all three men together entered the expansive resort in Glen Rose, some 70 miles southwest of Fort Worth, and headed toward a gun range.

Marcus Luttrell told CNN that Kyle, his friend, had gone to help Routh get "out of the house (and) blow off some steam." Another Kyle friend, former SEAL sniper program instructor Brandon Webb, explained that a range was a "familiar environment" for "military guys."

Around 5 p.m. Saturday, a hunting guide alerted authorities Kyle and Littlefield's bodies had been discovered "lying on the ground, covered in blood," according to Routh's arrest warrant, which was posted on CNN affiliate WFAA's website.

By then, Routh had taken off in Kyle's black Ford pickup, stopping first at his sister's house about 70 miles away in Midlothian. There, he told his sister and brother-in-law what he had done, telling them he had "traded his soul for a truck," the arrest warrant said.

He set off again.

Police finally caught up with Routh near his home in Lancaster, about 15 miles south of Dallas, around 8 p.m. Saturday. Despite a swarm of law enforcement, he managed to speed off in the truck -- but after spiking his tires, authorities were able to detain him without a scuffle by 9 p.m., Bryant said.

The story got intense, widespread attention in large part due to the victims, especially Kyle.

While serving as a sniper in Iraq, the Navy SEAL wrote he personally had 160 confirmed kills from a distance of up to 2,100 feet -- more than any other U.S. serviceman, in any conflict. This helped led Iraqi insurgents to nickname the 6-foot-2, 220-pound Texan "the devil" and put a bounty on his head, he said.