A Washington state man convicted of killing his mother 15 years ago will be freed from prison after investigators said new DNA tests linked another man to the crime.

Donovan Allen was expected to be released soon, after a prosecutor in southwestern Washington's Cowlitz County dismissed the case against him Tuesday, attorneys with the Innocence Project Northwest at the University of Washington Law School said Wednesday.

Allen was 18 when he found his mother, Sharon Cox, 49, in a pool of blood in 2000. He confessed to police after an overnight, 14-hour-long interrogation. Though he later recanted, he was convicted of aggravated first-degree murder and sentenced to life without parole.

Investigators said new DNA tests recently linked Cox's nephew, 42-year-old Brian Del Kitts, to the killing and he was arrested last week. The Daily News in Longview reports that he pleaded not guilty on Tuesday.

The Innocence Project Northwest requested the new DNA testing — with technology that is far more sensitive than was available 15 years ago — in an effort to exonerate Allen.

Policy director Lara Zarowsky told The Associated Press last week that prosecutors never suggested during Allen's trials that more than one person may have been responsible, the new testing excludes Allen as a suspect, and Allen should be freed from prison.

Police said the tests, performed by the Washington State Patrol Crime Lab, provided "compelling evidence" linking Kitts to the killing. Prosecutors dismissed the case against Allen without prejudice, meaning charges could be brought again if further evidence arises linking him. Allen's lawyers said the DNA test excluded him as a suspect.

Donovan said he was relieved to hear of Kitts' arrest, according to a statement released by the Innocence Project Northwest last week.

"He has taken everything from me," Allen said. "I lost my mother, then I lost my freedom and my family — this has destroyed so many lives."

Cox was the sister of Kitts' adoptive mother. Kitts was identified as a person of interest during the original investigation, Longview police said, but there wasn't enough evidence to charge him.

Among the items Innocence Project Northwest wanted retested were scrapings from Cox's fingernails, a cigarette butt, a gun, a phone cord, precise areas of the victim's clothing, and hair found in Cox's hand. Cowlitz County Superior Court Judge Marilyn Haan granted the request in June.