An immigrant from the U.K. who allegedly went on a killing spree in April was found dead in his jail cell Tuesday. 

Olaolukitan Adon-Abel, 26, was naturalized under the Biden administration when he served in the U.S. Navy. In April, police say he shot two people in DeKalb County, Georgia, and later shot and stabbed a Department of Homeland Security auditor as she took her dog for a walk. 

Authorities discovered him unresponsive in his cell and performed lifesaving measures before he was ultimately pronounced dead, The New York Post reported. 

His cause of death is not yet known, but officials don't suspect foul play.