Police officials have launched an investigation into the murder of a prominent criminal law professor at the Florida State University professor.

Dan Markel was fatally shot Friday at his Betton Hills home in Tallassee, Florida. Markel was killed by a single gunshot wound to his head.

Police officials said that there is no evidence of robbery or burglary and that Markel knew the murderer and might have himself answered the door. They have not yet identified a suspect nor did they determine any motive.

"We do believe that this was not a random act where he just surprised somebody," Officer David Northway said. "We believe that Mr. Markel, unfortunately, was the intended victim," abc News reports.

The Harvard grad, born in Canada, was a father of two boys (Benjamin Amichai, 3, and Lincoln Jonah, 5) and had recently got divorced. Wendi Jill Adelson, the 35-year-old ex-wife of Markel's who is also a fellow FSU professor, was shattered, disturbed and "scared to death," Local 10 reports.

"He had so many hopes and plans for his two little boys, Ben and Lincoln, whom he worried over with febrile intensity and loved that way too," Markel's friend Abigail Shrier told the Jewish Journal.

During Sunday's memorial service, Markel's well-wishers described him as a kind-hearted and a generous person.

"At the core what he cared most about was making sure that our criminal justice system actually produced justice, and he's going to be long remembered for that achievement," said Markel's friend Professor Ethan Leib.

Police have created a tip line with a $3,000 reward exclusive to the case. They urge delivery drivers, visitors, pedestrians or anyone - who was in Markel's neighbourhood between 10 a.m. and noon Friday, to call 1-891-574-4462 or contact police, CNN reports.