Bob Donaldson, Post-Gazette Clifford Aley peeks from behind his court papers, hiding his face from cameras, as a Mercer County sheriff's deputy wheels him into the Mercer County Courthouse for his trial on obstructing a murder investigation. Click photo for larger image.

MERCER, Pa. -- Private detective Clifford Aley went on trial yesterday in a homicide case, but he is not accused of killing anyone.

Instead, Mr. Aley is charged with repeatedly lying to state police about the disappearance and presumed death of Sandra Kay Baker.

During four years of deceit, Mr. Aley misled police and blocked them from finding clues that would have solved the mystery of Ms. Baker's slaying, Assistant District Attorney Tim Bonner said in his opening statement.

"He gave information which turned out to be significant lies that hindered the investigation and apprehension of the killer," Mr. Bonner said in outlining the four felony charges against Mr. Aley.

Then, facing the jury, Mr. Bonner identified the murder suspect as Billy Crea, who was engaged to Ms. Baker when she vanished on May 25, 2000.

Mr. Crea, 50, an electrician from Fredonia in Mercer County, has not been arrested or charged with any crime. His lawyer, James Ecker, said later he was reluctant to talk about an on-going trial involving somebody else.

"I have no comment other than Mr. Crea is still where he was when this began -- charged with nothing and innocent until proven guilty," Mr. Ecker said.

Mr. Aley's lawyer, Public Defender Dan Davis, opted not to make an opening statement to the jury yesterday. He said he probably will address the jurors after the prosecution concludes its case.

As for Mr. Aley, he came to court in a wheelchair. Pale, heavy and looking older than his 48 years, he sought out reporters and told them his health is being ruined because of inhumane conditions in the Mercer County Jail. He has been held there since his arrest in July.

Mr. Aley took notes while the prosecution played a tape of his first interview with police on June 18, 2000. Mr. Bonner said Mr. Aley began his string of lies that day.

In the recording, Mr. Aley said he did not know Ms. Baker and had never investigated her. Mr. Aley even denied knowing that his close friend, Mr. Crea, was engaged to her.

Under pressure from police four years later, Mr. Aley finally changed his story. He admitted that Mr. Crea had hired him to do an investigation on Ms. Baker in 2000. He found that she had been married six times and was still married to a Florida man when she became engaged to Mr. Crea.

Mr. Aley then dropped his bombshell. He said Mr. Crea told him he had strangled Ms. Baker after an argument about infidelity. Mr. Aley said Mr. Crea put her body in some sort of container and hid it in Mercer County.

But the prosecutor also used Mr. Aley's own words to suggest that Ms. Baker's slaying was premeditated, not the result of an argument.

Mr. Aley told police that Mr. Crea asked him on May 24, 2000, to dispose of Ms. Baker's car. That was the day before she disappeared.

Knowing that Ms. Baker was behind on her car payments, Mr. Aley called the finance company. He said he would supply information to help it repossess her vehicle.

On May 25, the very day Ms. Baker vanished, he called the company again. Mr. Aley said her blue 1988 Honda Accord was parked at the Shenango Valley Mall. Repo men hauled away her Honda and any evidence it contained.

Police did not find Ms. Baker's car until 2004. By then it sat in a scrap yard, crushed.

In his taped statement, Mr. Aley admitted to owning a blue 1988 Honda Accord that looked like Ms. Baker's. He said he bought the car the spring she disappeared. Mr. Bonner's implication to the jury was that the car gave Mr. Aley a ready explanation if anybody claimed he had been seen driving Ms. Baker's Honda.

Ms. Baker, 46 when she disappeared, would be 52 today. Mr. Crea stopped cooperating with police in 2000, but before he did, he said he last heard from his fiancee in a frantic phone call the afternoon she vanished. Mr. Crea said she told him she was in danger, but hoped to return home in a couple of days.