BOISE, Idaho (AP) - After almost 20 years on death row, Charles Irvin Fain may be set free after new DNA testing cast a long shadow of doubt on his conviction.

The 52-year-old Fain was found guilty in 1983 of kidnapping, sexually assaulting and drowning 9-year-old Daralyn Johnson.

But after the DNA tests on pubic hairs, his conviction was set aside by a judge who gave prosecutors until Sept. 4 to file new charges or free Fain.

``He's an innocent man who has been in jail for 18 years for a crime he didn't commit. It has been a tremendously long battle,'' said Spencer McIntyre, one of Fain's lawyers.

Daralyn was abducted as she walked to school in 1982. Her body was found by fishermen a few days later along the Snake River.

Fain, a handyman, moved into Daralyn's neighborhood shortly after her death. His attorneys said he passed a lie-detector test but was arrested and charged with murder.

Among the evidence against Fain were statements from cellmates who said he admitted to the crime and a girl who saw the abduction from a distance. Prosecutors also said a partially washed-out footprint near Daralyn's body resembled the sole of a tennis shoe found at Fain's home.

But the key evidence came from an FBI forensics expert, who said pubic hairs found on the victim's clothing may have been Fain's.

Last year, U.S. District Judge B. Lynn Winmill authorized $18,000 for new forensic tests. And last month, a Virginia laboratory said that none of the three hairs - one found on Daralyn's sock, the others in her underpants - was Fain's.

Two weeks ago, the judge set aside Fain's conviction.

According to the Death Penalty Information Center in Washington, 10 death row inmates have been exonerated by DNA evidence since 1990.

Prosecutors have not said what they plan to do. But prosecutor David Young acknowledged that winning another conviction against Fain could be difficult.

``If we do have the wrong guy, it's our job to identify that and get him out of there,'' Young said.

The girl's mother, Deanna Johnson, did not return a call for comment.

Fain is eligible to be moved off death row while awaiting a new trial or release, but he has asked to remain in the same cell where he has lived for years.

``He's used to it,'' defense attorney D. Frederick Hoopes said.