The completion of an independent investigation into the March 16 laboratory explosion at the University of Hawaii has been delayed to the end of June.

The University of California Center of Laboratory Safety was retained to conduct the investigation into the blast at the Pacific Ocean Science and Technology building, where a visiting researcher lost an arm in the explosion.

As part of the investigation, experts are testing materials. “The final completion of the investigation report is dependent on the testing and the test results,” UH said in a news release.

In April the Honolulu Fire Department released its investigation report indicating that a portable gas cylinder was the point of origin of the blast. Investigators determined the probable cause was a detonation of compressed gases sparked by a digital pressure gauge in a portable tank that was not designed for that use.

The Fire Department classified the blast as accidental.

Visiting researcher Thea Ekins-Coward, 29, was alone in the basement lab when the explosion occurred, and lost an arm. The lab is operated by the Hawaii Natural Energy Institute.