TV show sparks Melbourne cold case call

A TV program about cold case murders prompted a call to police about the killing of Melbourne nurse Ina-Doris Warrick, and now detectives want to speak to the caller again.

Ms Warrick, 25, was stabbed to death in her North Ringwood home in 1986 and the murder has not been solved.

But someone called police when her murder featured on "Million Dollar Cold Cases" on the Seven Network on March 29.

Police believe the caller has crucial information that a known suspect confessed to killing Ms Warrick, and want them to call back.

The next day, someone else called police about the double murder of Margaret and Seana Tapp in 1984.

Margaret Tapp, a 35-year-old nurse, and her nine-year-old daughter Seana were murdered in their Ferntree Gully home.

Police believe the caller has information on a suspect, a motive for the murders and details about the red ute seen outside their home.

Detective Inspector Michael Hughes said the two calls highlighted how it is never too late to tell police about a crime.

"We know that relationships change and circumstances can alter," he said on Thursday.

"It's a long time for someone to be living with the knowledge of a crime as serious as a murder.

"We'd love to be able to speak to these two people again, and hopefully give these families, who never stop grieving, some resolution."