A couple of people could make $1 million each today – simply by identifying the owners of two pairs of sports shoes that are the key evidence in two nasty murder cases in Victoria.

That’s the message out of the compelling Million Dollar Cold Case documentary series, which began on Channel 7 on Wednesday night.

The first beautifully told episode featured two of the 10 cases being reopened by the Victorian Police Homicide Cold Case squad, with the police paying a reward for information that leads to a conviction.

The first case features the deaths of mother and daughter Margaret and Seana Tapp, who were strangled in their beds at their Ferntree Gully home more than 30 years ago.

Seana, 9, was also brutally sexually assaulted – something the detectives who worked on the case originally can never forget.

“It was a horrible scene. That poor little girl who had her life cut short. She had her whole life ahead of her. I was absolutely gutted,” remembered Detective Senior Sergeant Ken Mahon, who is now retired.

The second case was the bloody murder of Cheltenham father Chris Phillips, 42, in his family home in 1989. It seemed it might be a random crime.

Mr Phillips was a family man, a civil engineer – with no clues as to why he might have been murdered.

But, as with the Tapp murders, police are convinced the victims knew their killers.

What makes this series fascinating is that the police openly detail and name all of the suspects and their alibis in both cases – while carefully stating that they are accusing no one and certainly not saying they are guilty of any crime.

All suspects are being reinvestigated.

In the case of Mr Phillips, the police revealed his wife was having an affair with a man at her local netball club and seeking a divorce at the time of his murder, but her husband was contesting it.

Chris Phillips was a family man whose death appeared to be a random attack.

“Did she play a part in his murder? We don’t know,” Detective Senior Sergeant Charlie Bezzina (now retired) said.

“[But] we are quite confident she didn’t strike the fatal blow.”

Police found a bloody print from a rare sports shoe at the scene and are convinced it belongs to the murderer.

In Margaret and Seana Tapp’s case, a man was charged with their murder but the charges were dropped after the evidence was contaminated.

There was a long list of suspects including the wife of a man Margaret had a relationship with and who owned the house she lived in – and a former policeman who was rejected romantically.

There was a print from a Dunlop Volley shoe left at the scene of these murders – and a suspicious red ute parked up the street on the day of the murders. Its driver was never found.

It’s clear how important this second chance at solving these cases is for the devastated families who were interviewed.

Police say killers rarely keep the murders to themselves and call on the public to do their duty and come forward to help them solve these cases.

There will be updates on progress as the series progresses.