Update - Bomb expert on OU blast: 'Not suicide'

A Norman, Okla., police bomb expert believes Joel Heinrichs III did not intend to kill himself when the explosive materials he carried detonated October 1 a short distance outside of a packed OU football stadium.

"I believe he accidentally blew himself up," Sgt. George Mauldin said.

Mauldin said Hinrichs, 21, an engineering student, had two to three pounds of triacetone triperoxide, commonly known as TATP, in a backpack in his lap when it exploded Oct. 1.

When asked if he believed Hinrichs meant to enter the stadium with the explosives, Mauldin replied, "I don't believe he intended for an explosion to occur at that spot (on the park bench)."

"Some of us will forever wonder what he (Hinrichs) was doing at that time, at that place," Police Chief Phil Cotten said.

Sgt. Mauldin's beliefs contrast with those of Heinrich's father, who has stated he believes his son intended only to kill himself, not others.

"Someone saw him fiddling with it (the backpack) shortly before the explosion occurred. I think he got cocky, and it went off," Mauldin said.

While the FBI says it has found no evidence that Heinrichs was involved in a plot with anyone else, the information delivered to the Norman city council certainly would not argue against it.

Mauldin said investigators found "quite a bit more" explosive material inside Hinrichs' Parkview apartment on Sooner Drive, southeast of Lindsey Street and Stinson Drive.

A pint-size Tupperware container on a counter was filled with TATP Hinrichs had manufactured, Mauldin said.

A pill bottle packed with TATP with a fuse stuck in it was found behind a computer, he said.

The FBI reported in November that 0.4 pound of TATP was found inside Hinrichs' apartment. TATP is the most unstable explosive known and is "the explosive of choice" in the Middle East, Mauldin said. "It is so volatile, even a small amount on the tip of a finger will explode if it comes within 8 inches of a match," Mauldin said.

Investigators also found a quantity of acetone and hydrogen, components necessary for manufacturing TATP, inside the student's apartment.

"We found evidence of him compressing TATP, which is foolhardy, given its properties," Mauldin said.

Making TATP is a seven-step process, Mauldin said, with the substance becoming explosive after three steps.

Bomb squad officers used great care in removing the material from Hinrichs' apartment for fear it would explode, Mauldin said.

"And we wanted to get it out of there quickly. The longer TATP sits, the more likely (it is) to explode spontaneously," he said.

Military rounds, metal fragments and a carefully kept record of his explosive experiments lead investigators to suspect that he was working on a more damaging product than the one he carried that fatal night. He also had apparently been conducting explosive tests at Red Rock canyon.

The meticulous planning would seem to rule out simple suicide, since he already had more than enough explosives to accomplish that task. As to whether there were other motives - or other people - involved, we may never know.