WILMINGTON, Del. — Police in Delaware say surveillance video shows a prominent national defense expert confused and disoriented in a downtown office building hours before his body turned up at a landfill.

Newark Police Lt. Mark Farrall said Wednesday that John Wheeler, 66, refused help from several people who approached him as he wandered around the Nemours Building in Wilmington as late as 8:30 p.m. Thursday.

Wheeler’s body was found Friday in a load of trash dumped at the Cherry Island Landfill. Police are investigating the death as a homicide.

A 1966 West Point graduate and Army officer at the Pentagon during the Vietnam War, Wheeler served the administrations of the last three Republican presidents. During Ronald Reagan’s time in the White House, Wheeler headed the Vietnam Veterans Leadership Program and helped get the Vietnam War Memorial wall built in Washington. Under George W. Bush, he helped develop an Air Force program to combat cyber attacks on U.S. weapons systems.

A tipster told police Wheeler was alive on Dec. 30 at 3:30 p.m. near an intersection about four blocks from the office of attorney Bayard Marin, who was representing Wheeler and his wife in a heated property dispute, and about a mile from an Amtrak station where Wheeler often caught the train to Washington. They found his car at the station.

Witnesses reported seeing Wheeler acting erratically on Dec. 29, multiple media outlets reported. A parking lot attendant next to the New Castle County Courthouse in Wilmington said Wheeler was unable to find his car, appeared disoriented and said he had been robbed. She said he was holding one shoe and was not wearing a coat over his suit despite cold weather.

Earlier that day, Wheeler had asked a pharmacist in New Castle for a ride to Wilmington. The News Journal of Wilmington said pharmacist Murali Gouro, who had filled Wheeler’s prescriptions in the past, said the former official looked upset.

Wheeler’s lawyer Marin said he last spoke with his client on Dec. 27, and did not know what he may have been doing in Wilmington three days later.

Wheeler was suing to block Frank and Regina Marini of Hockessin from continuing to build a new house across the street from his duplex. Wheeler argued that the Marini house did not comply with construction standards for new homes in the historic district. A Delaware Chancery Court judge denied Wheeler’s application for a temporary restraining order on Dec. 13.

Late on Dec. 28, several smoke bombs of the type used for rodent control were tossed into the Marini house, scorching the floors, Chief Deputy State Fire Marshal Alan Brown said.

The Marinis said in a statement that they offered "heartfelt sympathies" to the families of Wheeler and his wife, Katherine Klyce. Police have given no indication whether they believe the property dispute had anything to do with Wheeler’s death.

"It is one facet of the investigation," Farrall said.

In New York, police searched the condominium Wheeler and Klyce shared in a brick building on 124th Street in Manhattan, where they had lived for at least three years.

Building superintendent Jay Hosein said Tuesday that he saw Klyce last week, and that she seemed happy and cheerful.

"They were a very nice couple, very nice people," Hosein said.

Efforts by The Associated Press to contact Klyce have been unsuccessful. Wheeler’s family issued a statement through Newark police Monday asking for privacy.

Wheeler had twins, a son and daughter, by his first wife. Klyce has two daughters from a previous marriage.

Elizabeth Thorp, a board member of the Deafness Research Foundation, of which Wheeler had formerly been CEO, said the circumstances of his death were "too surreal."

She said he moved in a sophisticated crowd.

"This is not a guy who would end up in landfill or be murdered," she said. "It’s a gigantic loss."

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Associated Press writers Sarah Brumfield in Washington, David Dishneau in Hagerstown, Md., and Colleen Long in New York City contributed to this story.