CALCULATING killer Stephen Seddon was even prepared to risk the life of a disabled teenager in order to get his hands on his inheritance.

His 16-year-old nephew, along with both of his parents, were passengers in a hire car with Seddon at the wheel when it plunged into the icy waters of Manchester's Bridgewater Canal in March 2012.

He was not investigated for attempted murder, or even charged with a road offence.

In fact, Seddon was nominated for a Pride of Britain award after claiming to have gone back to try to save his parents from drowning.

The reality was the crash was a cold-blooded attempt to murder his parents as they drove home from a Mother’s Day meal.

It was only after Bob and Patricia Seddon’s death that police reinvestigated the accident and it emerged that Mr Seddon had confided in his GP that he feared his son had tried to kill him that day.

During witness interviews, it was clear that Mr Seddon had been suspicious of the canal incident in March as he knew his son was a capable driver and had received specialist driver training.

Mr Seddon also claimed that he had seen clips on his son's Sky box on methods of how to escape from a submerged car.

At the time of the accident, Seddon claimed to have swerved to avoid a brick in the road and plunged into 7ft of water - crashing into the canal in the only spot on the road without a safety barrier.

As he hit the water, Seddon said he had grabbed a car lock and smashed the window of the BMW to get out, before scrambling onto the car roof.

He then claimed to have kicked in a window to pull his nephew, who couldn’t swim, out of the submerged vehicle. The teenager, who has learning difficulties, was then helped to safety by two passing schoolboys.

Seddon then claimed to have swum back to rescue his father, just as firefighters arrived to rescue his mother.

Mrs Seddon later told journalists: "The doors would just not open. I thought I was going to die in that car."

Seddon staged a fainting episode minutes later, clutching his chest and collapsing to the ground.

But doctors found no problems with his heart and police also found no brick in the road.

Detective Superintendent Denise Worth, from Greater Manchester Police, said: "There was a lot of accounts from witnesses that something was a bit strange.

"He said he had hit a brick and had chest pains or could have had a blackout. He didn't really know why he went into the water.

"As a singular incident it was treated as an accident at the time. It was only when we got to the situation in July there was evidence that didn't fit and it was looked back on."

Asked if police could have done more, Ms Worth said: "In hindsight - it's a wonderful thing - possibly.

"He is a very, very convincing man. He revels in that kind of attention.

"I don't think there was any suggestion at the time that it was anything more than a road traffic accident."