2005 University of Oklahoma bombing

The blast took place less than 200 yards west of Oklahoma Memorial Stadium, where 84,501 spectators were attending a football game.

An off-duty police officer had noted Hinrichs talking with a local feed store owner about ammonium nitrate and had begun an investigation.

[5] The Federal Bureau of Investigation (FBI) and local authorities concluded in 2006 that Hinrichs acted alone and had no assistance from other groups.

They could not prove or disprove allegations that Hinrichs intended to enter the packed stadium and kill football fans along with himself.

[6] Shortly before halftime of the Saturday evening game between the Oklahoma Sooners and the Kansas State Wildcats, spectators inside the stadium heard an explosion.

University officials had decided against giving any further explanations to game attendees because they "didn't want to start any kind of panic.

The South Oval was open the next afternoon except for the immediate area of the explosion, so a broken glass door could be replaced and firefighters could finish spraying down the area with water to wash debris, chemicals and bodily fluids away from the sidewalk and a bus parked there before the preceding day's game.

In a press conference the next day, OU president David Boren identified Hinrichs, a 21-year-old mechanical engineering student, as responsible for the detonation.

He couldn't make friendships," and also said that Hinrichs began counseling at the university's on-campus health center two years earlier.

Instead, Hinrichs detonated triacetone triperoxide (TATP), an extremely unstable compound which can be made by mixing common household products like acetone, hydrogen peroxide and an acid catalyst.

[6] When investigators entered Hinrichs' apartment the morning after the explosion, they found more TATP and the necessary chemicals to make more of the substance.

[17] Hinrichs told friends and fraternity brothers that he liked explosives, and frequently experimented with building and detonating bombs made in or of plastic soda bottles.

[4] Hinrichs kept detailed records of many experiments he performed, done mostly at Red Rock Canyon in Caddo County, in the weeks prior to his death.

[17] Other items taken in the search included a thermometer, a slow cooker, rolls of tape, mixing bowls, and plastic containers.

[26] In August 2007, the university held an emergency drill to better prepare for future events during home football games.