DENVER -- Sen. Ken Salazar has asked the secretary of the Army to investigate a string of murders allegedly involving Fort Carson soldiers after they returned from deployments in Iraq.

Five soldiers from the 4th Brigade Combat Team of the 4th Infantry Division at Fort Carson have been charged with homicides, and a sixth has been charged with attempted murder.

"These incidents raise a number of troubling questions that merit serious scrutiny and attention," Salazar said in his letter to Secretary of the Army Pete Geren.

The most recent case is that of Robert Hull Marko, 21, whom police said confessed this week to killing a 19-year-old Colorado Springs woman he had met online.

On his MySpace page, Marko had written, "I'm becoming a cold hearted killer and can kill without mercy or reason." Before the alleged murder, Marko had received counseling due to "irregularities" during a mental health screening, but he had been declared fit for duty with no further treatment.

A fellow soldier from Fort Carson who said he served with Marko in Iraq posted a comment on Marko's MySpace page that Marko had a "huge imagination" and said that most of the things Marko said about Iraq never happened. "The Army had nothing to do with this except to give him a different place to live ... We never had a hard time. We had guard (duty) and we went out on patrols ... but as fire fights and death were to blame for this, it is fake. He never saw blood. He never saw action to shoot at," the poster wrote.

A high school friend of Marko's said, "One time (in high school), he said he was going to kill everybody.''

Maj. T.G. Taylor, a spokesman for the 4th Brigade at Fort Carson, said Marko "was identified to see a behavioral health specialist for reasons not related to deployment."

"From what I've read, there's no question this guy had some issues beforehand," said Dr. Andrew Sweet, a licensed psychologist and adjunct professor at Metropolitan State College in Denver. "That may speak to the issue of whether our military are doing a good job of screening people before they enter them into basic training."

Senator Asks If Soldiers Were Admitted Under Waivers

In the letter to Geren, Salazar asked for an inquiry into the personnel records of those soldiers involved in the violent incidents, including whether the soldiers were admitted into the Army under waivers, whether the soldiers had been flagged for mental health concerns, and what steps the Army had taken in response.

"In the Army's effort to meet its target recruiting numbers, the service has been issuing an increasing number of waivers to recruits who may not meet educational or moral standards," Salazar wrote. "Were any of the soldiers involved in these violent incidents at Fort Carson granted any such waivers, including felony criminal waivers, serious misdemeanor criminal waivers, or medical waivers related to mental health?"

Salazar Wants To Help Soldiers With 'Combat Stress'

The 4th Brigade Combat Team suffered the highest casualties of any Army unit assigned to Fort Carson during its tours in Iraq. All 3,600 soldiers in the brigade have been screened twice for mental health and medical issues since returning from the war, and 1,200 at-risk soldiers from the brigade are due to be rescreened for potential physical or mental health problems at the end of October.

Salazar also requests that Geren direct additional resources to Fort Carson for mental health treatment for soldiers and that the Army implement a pilot program at Fort Carson to provide additional pre- and post-deployment training on combat stress to both soldiers and families.

"I am also deeply troubled that in the seventh year of combat operations in the Middle East, the Army continues to struggle to provide quality mental health care for our soldiers. In addition to these tragic violent crimes, the Army's rates of suicides and suicide attempts have risen year after year. Although the Army has taken steps to implement screenings and provide counseling after a deployment, the Army is clearly overwhelmed by the scope of the problem. Too much time has been wasted studying the problem at the expense of implementing real solutions ... I have become convinced that because of the scope and nature of the problems related to combat stress, Army medical providers alone are unable to effectively address these challenges."

He suggested a pilot program that other units have used and request that the secretary immediately visit Fort Carson to learn what measures are being taken, what more could be done to prevent similar tragedies in the future, and what additional resources are needed.

"This pilot program would allow Fort Carson to utilize outside entities to provide soldiers tools that can help them proactively manage combat stress. Special Forces units within the Army have begun implementing similar programs with their own funds. Army Medical Command, as I understand it, has so far resisted this type of program. I ask that you immediately review the idea and employ it as a pilot program at Fort Carson," Salazar said.

The letter was also sent to Lt. Gen. Eric B. Schoomaker, surgeon general of the Army; Maj. Gen. Mark Graham, commanding general of Fort Carson; and Col. Kelly Wolgast, commander of the Evans Army Community Hospital.

Graham said he spoke to Salazar by phone as well, and in response, created a task force to look into the matter.

"We too are very concerned about these horrible acts. Therefore, I have established a comprehensive task force to identify any commonalities between previous homicides by our soldiers or former soldiers. This task force is comprised of representatives from legal, medical (to include behavioral health), law enforcement and human resources, and will report directly to me," Graham said.