An Ohio police department issued a public apology Friday to the family of a 14-year-old girl whose murder went unsolved for 40 years after admitting that detectives on the case botched the investigation.

Christie Lynn Mullings was found beaten to death behind a shopping center in Columbus on Aug. 23. 1975.

Columbus Police Sgt. Eric Pilya, head of the cold case unit, said “improper investigative techniques” by detectives investigating the killing led to the arrest of an innocent man and impeded efforts to apprehend the man detectives now say killed the young girl, Henry Newell Jr.

At a news conference, Pilya said he wanted to “formally and publicly apologize” to Christie’s family who for years believed Newell was the killer. 

Newell died in 2013 at age 63. Two relatives came forward after his death and told police Newell had confessed to killing the girl, re-igniting the cold case investigation which has been closed.

“It’s kind of bittersweet,” Pilya told reporters. “I think it would have been better if the suspect had been alive to pay for his crime but this will have to do.”

The man tried for the crime, John Carmen, had severe developmental disabilities, The Columbus Dispatch reported Friday.

He pleaded guilty but when questions were raised about his mental capacity the plea was withdrawn.

A jury found him innocent in 1977, the paper reported.

Newell testified at Carmen’s trial that he saw him man swinging a board, the Dispatch reported. The jury heard Newell testify that he found the girl, who was already dead.

Pilya said at the time Newell said he placed a shirt over the victim’s face and touched the murder weapon.

The sergeant said those statements were incriminating enough to make Newell a suspect.

“I don’t know why he wasn’t pursued back then,” Pilya said.

Christie’s sister Melanie Miller told Fox 28 the family appreciated how the Columbus police conducted the cold case investigation.

She complained the family was treated like criminals after the murder.

She also said the family wants to know why Newell was ruled out as a suspect.

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