Tallahassee police have released photos of a gunman’s vehicle in hopes it will lead to an arrest in the unsolved murder of Dan Markel.

Markel was a criminal law professor at Florida State University, but the 42-year-old was born in Toronto. Markel was murdered in his Florida home exactly one year ago Saturday in what Tallahassee police have called a targeted shooting.

Markel, a father of two, was shot minutes after getting home on July 18, 2014. He was on the phone at the time and told an unidentified caller: “Someone is in my driveway.”

A lone gunman followed Markel into his garage and shot him in the head. Markel died in hospital a few hours later.

The shooting occurred just days after Markel posted an article about the death penalty on his blog. He had received threatening comments in relation to posts on the same website in 2012.

“Is it possible that some of his scholarship and literature created some enemies? I guess that’s as possible as any of the other scenarios,” Markel's friend, Reggie Garcia, told CTV Toronto.

The silver-coloured Toyota Prius in the photos released by police has one black passenger side mirror and a missing tow bolt.

Tallahassee police are asking anyone who might recognize the vehicle to contact them. The reward for information that leads to an arrest and conviction has been increased from $25,000 to $125,000.

With a report from John Musselman