JACKSONVILLE, Fla. -

A man convicted of first-degree murder in the 2009 shooting death of another man at a gas station was sentenced Wednesday to life in prison.

In March 2009, then-19-year-old Cary Austin shot and killed 41-year-old Tracy Lewis at a BP gas station on Philips Highway.

Lewis was pumping gas in his car when he was shot in the head, prosecutors said.

Investigators said several witnesses identified Austin as the killer, but they said they did not know a motive for the killing.

They said the two were strangers.