LOS ANGELES — A man who spent two decades in prison after being wrongly convicted of murdering his lover filed a federal lawsuit Tuesday accusing Southern California sheriff’s investigators of manufacturing a case against him.

Horace Roberts, 61, is suing Riverside County and officers from its Sheriff’s Department, alleging they failed to turn over key evidence to prosecutors.

Roberts was exonerated and freed last year after DNA testing of crime scene evidence led to the arrests of Googie Harris and Joaquin Leal in the 1998 strangling of Terry Cheek.

Harris was Cheek’s estranged husband and Leal is the nephew of Harris. Both have pleaded not guilty.

Harris set up Roberts to take the blame and investigators fabricated police reports, suppressed evidence and shaped testimony, said Steve Art, one of the attorneys representing Roberts.

No evidence at the scene tied Roberts to the killing, the lawsuit says.

The Riverside County Sheriff’s Department said it doesn’t comment on pending litigation.

Suppressed evidence against Harris and Leal included a watch and a length of rope found with Cheek’s body on a lake shore, according to the lawsuit.

“She was strangled with a rope,” Art said. “That same rope was the rope used by her husband on a dog run at his property. That fact was known by police.”

After the killing, Roberts was interviewed by investigators five times “for hours and hours,” while Harris was questioned just once “for a short period of time with no follow-up,” Art said.

Detectives also didn’t seriously consider claims from Janet Corsi, a friend of Cheek who told police that Harris was threatening and abusive to his estranged wife shortly before the killing, the attorney said.

The lawsuit demands a jury trial and seeks unspecified compensatory damages.

In 2017, crime scene evidence was sent to the California Department of Justice laboratory in Riverside.

DNA on the watch found with Cheek’s body was matched to Leal in March 2018, prosecutors said, and he and Harris became the focus of a new probe. Harris and Leal were arrested in October last year. They’re in custody awaiting trial.

Roberts said in a statement that he can’t get back lost time but hopes for reforms to help prevent future injustice.

“I hope this lawsuit will bring to light the injustice that I suffered and cause officials and lawmakers to look carefully at reforming our criminal justice system,” he said.

Since tossing his prison clothes in a trash can after serving more than 20 years, Roberts reunited with family in South Carolina, Art said.

“He is getting acquainted with his kids and grandkids,” the attorney said. “And he is working to recover from the psychological harm that all that time in prison caused.”