AUSTIN, Texas (CBSDFW.COM/AP) – Federal officials say the suspect in a series of fatal Austin package bombings used PVC pipe casing, a metal pipe and shrapnel in his attacks that killed two people and seriously injured four others.

Authorities on Monday released an affidavit used to support an arrest warrant for suspect Mark Conditt. Investigators used bomb evidence, video surveillance, interviews and phone records to chart a path to Conditt.

Austin Police say Mark Conditt died after he set off an explosive device inside of his vehicle in a suburban Austin hotel parking lot as SWAT teams closed in.

Police say he blew himself up March 21 as officers closed in to make an arrest.

The document still redacts details about witnesses who were interviewed, phone numbers and places where police say Conditt purchased his materials.

Authorities also dismissed an arrest warrant that had been issued hours before police say Conditt killed himself.

The documents didn’t mention a possible motive for the bombings.

Conditt left behind a 25 minute recording on his phone describing the seven bombs he constructed, Austin Police Chief Brian Manley said the day Conditt died.

The chief said Conditt talked about problems in his personal life in a what Chief Manley called a video confession found on his phone after his death.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)