Salt Lake City police detectives believe they know what happened.

They just don't know why.

The investigation into the Trolley Square shooting rampage Feb. 12 apparently is hinging on the unanswered question: why?

Why did 18-year-old Sulejman Talovic go on a killing spree inside the crowded mall, killing five people and wounding four others before dying in a shootout with police?

On Friday, Salt Lake City police said detectives have been reviewing their evidence, witness and survivor accounts to make sure everything is consistent.

"They feel pretty comfortable they know where people were and when, where the shooter was," Salt Lake City police detective Jeff Bedard said Friday. "We're trying to figure out why."

Police Chief Chris Burbank said they have found nothing so far that points to a motive, other than that Talovic was a "very disturbed individual who felt that this was his only option in life."

"It's unfortunate that society, you know, we have these things come up every once in a while, and we haven't come up with a solution to prevent it," Burbank told the Deseret Morning News.

Burbank said they continue to trace the guns that Talovic used, a 12-gauge shotgun and a .38-caliber pistol. Police are still tracking down people who had contact with Talovic so they can be questioned.

"We're still going through the process of looking at anyone that he may have had contact with that had a computer," the chief said, adding that homicide detectives have not found any connection between the young man and his victims or the Trolley Square mall.

Whatever the detectives have learned, they've gone to great lengths to keep quiet.

Police have refused to release many basic details of the shooting rampage, including how many shots were fired by both Talovic and officers, the make and model of the guns he used, where they were purchased and what Talovic said to his victims and officers before he died.

"He really said nothing," Burbank said. "It's my understanding that he used a curse word and that's it."

A series of records requests filed by the Deseret Morning News under the Government Records Access Management Act for 911 tapes, transcripts and incident reports have all been denied. The newspaper has filed an appeal to the Salt Lake City Attorney's Office.

Bedard said investigators want to listen to the 911 tapes again before making them public.

"They want to review every one first and listen to every tape to make sure that none of them violate the privacy of those that called," Bedard said.

Burbank said that he believes his detectives will uncover a motive.