A grieving mum helped clear her daughter’s ‘killer’ who was wrongly jailed for 20 years after launching her own investigation into the case.

Christopher Tapp, 42, was sentenced to life in prison for aiding and abetting the rape and murder of 18-year-old Angie Dodge in Idaho Falls, northwest region of US, in 1996 – a crime which he falsely confessed.

But he was exonerated on Wednesday thanks to Angie’s mother Carol Dodge who demonstrated unbelievable determination and strength to solve the homicide and bring the case to a close.

Mr Tapp told a judge at his hearing: “I’m thankful I’ve been given this second chance at life.

“I’ve wasted 20 years of my life for something I never did.”

The case was also blown wide open thanks to a new forensic technique called genetic genealogy which pairs DNA with genealogy databases.

Mr Tapp became a suspect when the police contacted him for information about his friend who they had arrested in relation to a different rape.

Vanessa Potkin, director of the post-conviction litigation at the Innocence Project, said: “Police threatened him with the death penalty and told him that if he just told them what they wanted to hear, they would give him immunity.”

He confessed to the murder despite not being involved.

He was convicted of rape and murder in May 1998 and handed a life sentence.

Devastated Carol publicly stated at the time that she did not believe Mr Tapp killed Angie. She immediately began fighting for his release from prison.

She asked for the confession tapes and listened to over 70 hours of interviews – only half the amount of the tape.

During the interviews, police could be heard pushing Mr Tapp to name his accomplice and promising him leniency if he complied, The Sun reports.

She contacted a false confession expert in 2014 who in turn contacted the Innocence Project.

Lawyers for Mr Tapp filed post-conviction motions based on new DNA testing and in 2017 the prosecutor agreed to a new deal.

The court cleared Mr Tapp of rape but not of murder and he was freed due to the time he had already served.

Mrs Dodge was also trying to track down the person involved in her daughter’s murder and eventually contacted CeCe Moore, a genealogist with Parabon, a consultancy firm.

Ms Moore built up a new DNA profile from a degraded sample and identified several relatives in a genealogy database.

Thanks to her work Brian Leigh Dripps, who had lived across the street from the victim at the time of her murder, was identified.

Investigators confirmed the crime scene DNA was his and Dripps was arrested.

During his interview, he said he acted alone and did not even know Mr Tapp.

Carol’s son, Brent, said in a statement: “We’re safe tonight. The bad guy is behind bars.

“We express our gratitude for the prayers, the faith and hope to help our mother soldier on.

“This is a great day for our family. Angie was a wonderful, bright young woman.”

Carol told the New York Times on Friday: “This has literally shattered my family as if we were a piece of glass.

“There is no way to pick up the pieces.”

Daniel Clark, the Bonneville County prosecutor, moved on Wednesday to dismiss all the charges against Mr Tapp.

Dripps, who is currently being held in the Bonneville County Jail is due to appear in court in August.