An autopsy is scheduled Thursday to determine the official cause of Jimmy Lee Dykes' death, according to the FBI.
Dykes was killed following a firefight with law enforcement after a nearly week-long hostage standoff in Midland City.
A shooting review team from Washington D.C. arrived in Midland City Wednesday to gather more information.
Bomb technicians with the FBI, the Alabama Department of Investigation and Dothan Police have finished their part of the investigation.
Agents did not remove any more devices beyond the two explosives found on Tuesday. One was safely uncovered from the bunker. The other was found in the pipe that agents used to talk to Dykes.
Flash bangs were used to stun Dykes before rescuing Ethan, according to FBI officials.
An evidence response team will remain at the bunker to search the scene. The FBI expects this process to take another two to three days.
Meantime, family members of the bus driver who tried to protect Ethan told NBC News they have already forgiven Dykes.
"Every time my dad got on a bus, it wasn't for transporting somebody else's kids, it was HIS kids -- he took them as his own. And I think that's the reason why my dad did what he did," said Poland's son, Aaron Poland.
The Poland family said it brought them great happiness to know Ethan is home safe.