Denver - Fort Carson soldiers returning from deployment in Iraq are suspects in at least five slayings, and officials want to know why.

    Commander Maj. Gen. Mark Graham announced Friday a task force will examine any commonalities in the five killings, all committed in Colorado, allegedly by soldiers from the post's 4th Brigade Combat Team in the past 14 months. A sixth BCT soldier faces an attempted murder charge.

    "We have many great young Americans in our Army who have volunteered to serve during a time of war, almost all of whom are great citizens," Graham said in a statement. "However, we too are very concerned about these horrible acts."

    Fort Carson also plans to re-screen about 1,200 soldiers from the brigade for potential physical or mental health problems.

    Earlier Friday, Colorado Sen. Ken Salazar asked Army Secretary Pete Geren to investigate the slayings. Officials learned of the latest on Monday, when Spc. Robert Hull Marko, 21, led investigators to the body of 19-year-old Judilianna "Judi" Lawrence, whom he met on the social networking Web site MySpace, according to an arrest affidavit released Tuesday.

    The affidavit said Marko told investigators he had violent sex with Lawrence before slitting her throat and leaving her to die in the foothills west of Colorado Springs. His next court appearance is Monday.

    The issue of homicides by combat-stressed veterans gained national prominence in January, after The New York Times reported that at least 121 Iraq and Afghanistan war veterans had committed a killing in the United States or been charged in one.

    Karen Linne, a spokeswoman for Fort Carson, said commanders two months ago ordered squad leaders and team leaders to reevaluate soldiers to see if they need additional help following concerns raised after another soldier from the unit was linked to a double slaying.

    Pfc. Jomar Dionisio Falu-Vives, 24, and Spc. Rodolfo Torres-Gandarilla, 20, face attempted murder charges in the May 26 wounding of Capt. Zachary Zsody, who was shot twice while standing at an intersection. An arrest affidavit released in August said an AK-47 used in the Zsody case was found in Falu-Vives' apartment and it was also used in the June 6 deaths of two people gunned down on the street while putting up signs for a garage sale.

    Killed were Cesar Ramirez Ibanez, 21, and Amairany Cervantes, 28. Prosecutors filed murder charges against Falu-Vives on Sept. 15.

    Three other members of the unit were accused in the slayings of two soldiers. Bruce Bastien Jr. was sentenced last month to 60 years in prison. He pleaded guilty to accessory to murder in the December shooting death of Kevin Shields, and conspiracy to commit murder in the August 2007 death of Robert James.

    Bastien, and co-defendant Kenneth Eastridge, both agreed to testify against fellow Iraq war veteran Louis Bressler, the alleged triggerman.

    Eastridge pleaded guilty July 11 to accessory to murder in Shields' death and will be sentenced Nov. 3. Bressler is scheduled to go on trial in the Shield slaying Nov. 3, while his trial in the James homicide is scheduled for Dec. 1.

    "Those who committed these violent crimes should be brought to justice," said Salazar. "But these tragedies also raise a number of questions from the backgrounds and service records of these soldiers, to whether they received waivers to enter the service, to the adequacy of mental health screening and treatment within the Army."

    Falu-Vives and Torres-Gandarilla, accused together in one case and Bastien, Bressler and Eastridge, accused in the two slayings, served in Iraq last year with the 2nd Battalion of the 4th Brigade Combat Team. There weren't any immediate indications that both sets of men knew each other.

    Marko was a mortarman with Charlie Company, 3rd Squadron, 61st Cavalry Regiment, of the 4th BCT and served from February 2007 until February of this year.