About 3:30 p.m. Thursday, John P. Wheeler III, 66, was seen in Wilmington in the area of 10th and Orange streets, said Newark police spokesman Lt. Mark Farrall.

Newark police returned Monday to the Cherry Island Landfill in Wilmington, where Wheeler’s body was found at 10 a.m. Friday after falling out of a trash truck.

Farrall said that the crime scene has not yet been located.

“Because of his background, we have been in contact with the FBI, but it remains our investigation,” Farrall said today.

Wheeler had a prominent role in getting the Vietnam Veterans Memorial built in the 1980s and worked in the last three Republican presidential administrations.

A Newark police crime-scene unit was inside Wheeler’s home at 108 W. Third St. in New Castle all day Friday, Saturday and Sunday, according to neighbor Ron Roark.

By Monday morning, the crime-scene tape had been taken down.

“At this point … we’re still trying to locate where the crime occurred,” Farrall said Monday.

Detectives also had not yet pinpointed the trash bin on the east side of Newark into which Wheeler’s body was dumped, Farrall said. Tracing the trash truck driver’s route, police determined Wheeler’s body could have been dumped in any of 10 trash bins.

The cause of Wheeler’s death is awaiting toxicology results and further forensic testing, Carl Kanefsky, spokesman for the state Department of Health and Social Service, said today.

Roark, who lives next door to Wheeler’s home in a circa-1900 duplex at Third and South streets, said Monday he had met Wheeler only once and rarely saw him. But for four days around Christmas, Roark and his family heard a loud television in Wheeler’s home that was constantly on, but no one appeared to be home, Roark said.

“It was so loud, we could hear it through the walls, and we found that strange,” Roark said.

Because Wheeler and his wife, Katherine Klyce, worked in Washington and New York, they were frequently away from home. Records show Wheeler and Klyce were established residents and registered to vote in Delaware.

“But they were never home,” said Roark, who has lived next door to Wheeler for seven months.

Klyce, who owns a Cambodian silk company based in New York, did not return phone calls or e-mails Monday, and her whereabouts are unknown.