Updated at 8:50 p.m. ET: Brandon Friedman, an Army combat veteran in Afghanistan and Iraq and author of the highly regarded memoir "The War I Always Wanted," warned against linking post-traumatic stress disorder or conditions at Joint Base Lewis-McChord to Barnes' alleged behavior.

There's "obviously no question of a tie between combat and PTSD," Friedman said in a Twitter message to msnbc.com. "But having PTSD doesn't signify a propensity to murder Americans."

Mount Rainier National Park remains closed until at least Saturday, park officials said.

Barnes was from Riverside County, Calif., and as a teenager attended a community day school for expelled and troubled students, the Press-Enterprise newspaper reported. A young man who answered the door at the family's home said the family had no comment, the paper said.

Original post: The Iraq war veteran believed to have killed a park ranger Sunday was last stationed at a Washington base considered among the military's most troubled facilities, where suicides and violence among service members have reached record levels.

Authorities said they believed Benjamin Colton Barnes, 24 — who was found dead Monday, apparently of hypothermia, in Mount Rainier National Park — shot and killed Park Ranger Margaret Anderson, 34, on Sunday. He is also believed to have shot and wounded four people, two of them critically, earlier in the day at a New Year's party in Skyway, near Seattle, authorities said.

Barnes, a private first class, was discharged from the Army for misconduct in 2009 after he was charged with drunken driving and improperly transporting a privately owned weapon at Joint Base Lewis-McChord, Wash. Lewis-McChord has drawn national attention for widespread problems with post-traumatic stress disorder among service members returning from Afghanistan and from Iraq, where Barnes served in 2007 and 2008.

In July, the mother of Barnes' young daughter said in court papers seeking a protection order that he "has possible PTSD (post-traumatic stress disorder) issues," NBC station KING of Seattle reported. In seeking sole custody of the girl, she said Barnes was suicidal and "gets easily irritated, angry, depressed and frustrated." 

The woman said Barnes had numerous weapons in his home, including firearms and knives, adding: "I am fearful of what Benjamin is capable of with the small arsenal he has in his home and his recent threat of suicide."

A year ago, the military newspaper Star and Stripes rated Lewis-McChord as the most troubled base in the entire U.S. military, with multiple criminal and military investigations under way into troops' behavior and the quality of the medical and mental health care for service members returning from the war.

And that was before the base set a record for presumed suicides in 2011, with 12, according to military statistics scheduled to be released this month but obtained by The Tacoma News-Tribune.

The Army directed base officials last year to focus specifically on the mental health of members of the 5th Stryker Brigade, which saw heavy action in Afghanistan in 2009 and 2010. Barnes served with a Lewis-McChord Stryker brigade, although officials said they didn't immediately know whether it was the 5th.

The problem isn't confined to Lewis-McChord. In a paper for the Army War College last year (.pdf), Army Col. Ricardo M. Love reported that "veterans returning from Iraq and Afghanistan are diagnosed with Post-Traumatic Stress Disorder (PTSD) at an alarming rate."

A 2008 RAND Corp. study indicated that 18 percent of all service members returning from Iraq and Afghanistan since 2001 had "PTSD or major depression." Only about half seek treatment, it said.

"Although Commanders are conducting tough and realistic training prior to deployment, the high number of returnees diagnosed with PTSD indicates we are not doing enough," Love concluded.

But the problem is especially severe at Lewis-McChord, which the Los Angeles Times profiled as "a base on the brink" just last week.

"I can tell you that in the last two years, we have had 24 instances in which we contacted soldiers who were armed with weapons," Bret Farrar, police chief in nearby Lakewood, told the newspaper. "We've had intimidation, stalking with a weapon, aggravated assault, domestic violence, drive-bys."

The issues have come to widespread public attention after Lewis-McChord's heaviest year of deployments in Iraq and Afghanistan, where 18,000 soldiers from the base served in 2009-10.

The base, near Tacoma about 50 miles south of Seattle, has seen numerous violent incidents, leading to several charges and convictions of soldiers for serious crimes. According to The Seattle Times, they include:

• Pfc. Dakota Wolf, 19, who is charged in the stabbing death Nov. 30 of a 19-year-old woman in a Seattle suburb while AWOL.
• Sgt. David Stewart, 38, who killed himself and his wife after leading authorities on a high-speed chase in April. Their 5-year-old son was found dead at home.
• Spc. Ivette Gonzalez Davis, 24, who was sentenced to life in prison in August 2010 for shooting two soldiers and kidnapping their baby.
• Sgt. Sheldon Plummer, who was sentenced to 14 years in prison for strangling his wife in February 2010.

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