Provincial police hope a case chronology video can help breathe life into a four-decade-old homicide.

At a news conference Thursday, OPP unveiled a YouTube video detailing the death of 14-year-old Sarnia girl, Karen Caughlin.

Caughlin was dropped off early on March 16, 1974, in front of a friend's house on Brock St. South in the city. Investigators say she never entered the home and a farmer discovered her battered body later that morning in a shallow ditch by then 6th Side Road or Freer Road, now known as Plowing Match Road northwest of Petrolia.

At the news conference, the OPP Criminal Investigations Branch said they are looking at a nine-hour gap between when Caughlin was last seen and when her body was discovered 22 km away.

Police are hoping the seven minute video will reinvigorate the memories of Sarnia residents. Authorities want to speak with anyone who may have seen or been with Caughlin on Friday, March 15 at locations in the community or at Sarnia Collegiate Institute and Technical School.

Police have said the autopsy revealed that Caughlin's injuries were consistent with having been struck by a vehicle. However, circumstances such as her purse being located several days later in a ditch north of Petrolia, led investigators to rule her death a homicide.

Even a $50,000 reward for information leading to the conviction of her killer hasn't led police to an arrest in the case.

With files from The Canadian Press