Updated

Fort Hood shooter Ivan Lopez's rampage followed an argument over the denial of his request for leave and did not appear to be due to some ongoing mental problem, an Army official said Monday.

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The word came as officials announced findings of their ongoing investigation, which included interviews with more than 1,100 people and a recreation of the shooting last Wednesday, which left four dead including Lopez, and 16 injured.

“We only have one suspect,” said Chris Grey, spokesman for the Army’s Criminal Investigation Command. “We are fully committed to this investigation and we will continue to pursue investigatively all leads."

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Grey, who was flanked by other law enforcement officials, did not take questions at the brief Monday news conference, and said he would not divulge any information that could jeopardize the investigation. But confirmation that an argument of a request for leave had immediately preceded the shooting seemed to further put to rest prior speculation that the 34-year-old Army specialist's Lopez's spree may have been related to Post-Traumatic Stress Disorder. Although he had reportedly been treated for mental issues including depression, military officials had expressed skepticism that his four-month tour in Iraq as that war wound down could have caused PTSD.

One complicating issue in the probe is the sheer size of the crime scene, Grey said, noting that it was comparable to two city blocks. The spree began in one building of the sprawling complex, where Lopez, who was 34, first pulled his .45-caliber Caliber Smith & Wesson handgun and killed one, injuring 10.

"The deceased and one of wounded had been involved in the verbal altercation with subject," Grey said.

Lopez then got in his personal vehicle and drove slowly from the building. As he drove, he fired his weapon at two soldiers, wounding one, Grey said. After reaching another building, to which he had been assigned, he shot one soldier, who later died, and then wounded two more soldiers. At one point, he fired at the windshield of an occupied car, wounding a soldier, then proceeded to a medical building, where he shot and killed a soldier at desk and wounded another person.

"At this point we do not know why he entered the building and we may never know,” Grey said.

When he encountered a Fort Hood Military Police officer who had responded to the shooting, Lopez had a verbal exchange with her, Grey previously said. The officer fired a shot at him that missed, and then Lopez put his gun to his head and killed himself.

Killed were Army Sgt. Timothy Owens, of Illinois; Staff Sgt. Carlos Lazaney Rodriguez, 38, of Aguadilla, Puerto Rico and Sgt. 1st Class Daniel Ferguson, 39, of Florida.

From the time the first 911 call was placed to the point Lopez killed himself, approximately eight minutes elapsed, Grey said. More than 35 rounds of .45-caliber ammunition were recovered. Three spent spent shell casings were found in Lopez's car and 32 more were discovered throughout the crime scene.

Lopez, a married father of four, had only been assigned to Fort Hood earlier this year, working as a truck driver. His deadly attack came at the same Killeen, Texas, base where in 2009 U.S. Army Maj. Nidal Hasan killed 13 and wounded 30. Hasan, a psychiatrist who had become a radical Muslim while serving in the military, represented himself at a military trial after clashing with his appointed attorneys and was sentenced to death in August.

More information will be released as the investigation continues, Grey said.

"We sincerely hope that our efforts to diligently seek the truth will in some small way provide comfort to the families of the deceased and wounded in this difficult time," Grey said.