(CNN) — In a grim pattern that has become all too familiar, another campus has been shattered by gunfire, this time at Old Dominion University in Virginia, where an attacker cloaked violence in the language of religion.

Federal authorities are investigating Thursday’s shooting at Old Dominion University as an act of terrorism after identifying the gunman as Mohamed Bailor Jalloh, 36, a former member of the Virginia National Guard who previously served prison time for attempting to aid the terrorist group ISIS.

Devoted ROTC instructor Lt. Col. Brandon Shah, a father and husband, was killed in the attack. Two others were hospitalized with injuries, university police Chief Garrett Shelton said, noting all three victims were affiliated with the university.

Federal investigators say they are still piecing together the events leading up to the attack and what led Jalloh to carry out the shooting.

The case has drawn renewed scrutiny to Jalloh’s past, including a terrorism conviction nearly a decade ago that followed an investigation officials said kept them “up at night,” as well as the circumstances surrounding his early release from prison.

During the earlier investigation before his stint in prison, investigators were made aware that Jalloh had expressed admiration for the 2009 Fort Hood shooting rampage, when Army psychiatrist Nidal Hasan killed 13 people and wounded dozens at a Texas military base.

A former National Guard member with a terrorism conviction

Jalloh, a naturalized US citizen born in Sierra Leone, served as a combat engineer in the Virginia National Guard between 2009 and 2015, according to a US Army official.

During a 2016 investigation, authorities learned he had begun consuming online lectures from a deceased Al-Qaeda leader and ultimately decided not to reenlist after leaving the Guard.

That same year, federal prosecutors said Jalloh attempted to assist ISIS. He sought to obtain weapons he believed would be used in an attack carried out in the group’s name and also tried to send money to the terrorist organization, according to the Department of Justice.