Officer presumed murdered instead fatally shot himself in garage, police say

A manhunt spawned by the death of an on-duty police officer, including a SWAT team and highway closures, has been suspended after the medical examiner's office on Tuesday ruled that he had died of a self-inflicted wound.

Police in Maryland are working to piece together the events that led to the death of Thomas Bomba, a 13-year veteran of the Montgomery County Police Department near Washington, D.C., who called for back up just minutes before he fatally shot himself, authorities said.

Bomba, 38, told dispatchers that he'd been flagged down by someone "regarding disorderly subjects" in a public parking garage on Monday morning, just moments before he apparently shot himself, the department said.

Investigators had been treating the death as a homicide and previously said there was no evidence to suggest the shot was self-inflicted.

It said Bomba was wearing his body-worn camera at the time, but it had not been activated.

"We continue to evaluate evidence collected at the scene as part of our commitment to completing a thorough and exhaustive investigation," the department said in a statement Tuesday. "The outpouring of support from the community has been greatly appreciated during this trying time."

Montgomery County Police Chief Marcus Jones mourned Bomba as a "very dedicated officer" who worked for the department's Patrol Services Division. He is survived by his wife and two children.

ABC News' Sarah Shales contributed to this report.