DOVER, Del. — A prominent national defense consultant was seen alive in downtown Wilmington less than 24 hours before his body was found in a load of trash at a landfill, police said Tuesday.

John P. Wheeler III, of New Castle, was seen around 3:30 p.m. Thursday near the Hotel du Pont, about two blocks from the office of an attorney who was representing him and his wife in a property dispute, Newark police said.

Wheeler’s remains were found around 10 a.m. Friday as a refuse truck dumped its load at the Cherry Island landfill in Wilmington. Investigators say he was slain.

Police say the truck collected all its trash from about 10 commercial disposal bins in Newark, several miles from Wheeler’s home in the historic district of New Castle.

Newark Police Lt. Mark Farrall said the information about Wheeler’s whereabouts before he died came from a caller’s tip that police confirmed. He said police also were reviewing video surveillance tapes from downtown Newark.

Farrall said Newark police have consulted with the FBI about the case but wouldn’t say what assistance, if any, federal investigators are providing.

Wheeler, 66, served three Republican presidents and helped to get the Vietnam Veterans Memorial built.

Friends say they traded e-mails with Wheeler — who had not been reported missing — around Christmas. Wheeler also had been scheduled to take an Amtrak train from Washington to Wilmington on Dec. 28, but it’s not clear if he ever made the trip.

Family members may not have reported him missing because they were out of town, Farrall said.

Efforts by The Associated Press to contact his wife, Katherine Klyce, were unsuccessful, but his family issued a statement through the police department.

“As you must appreciate, this is a tragic time for the family. We are grieving our loss. Please understand that the family has no further comment at this time. We trust that everyone will respect the family’s privacy.”

Wheeler had a twin son and daughter, John and Katie, by his first wife, Elisa. Klyce has two daughters from a previous marriage.

Wheeler followed in his decorated father’s footsteps and attended the U.S. Military Academy at West Point. After graduating in 1966, in the midst of the Vietnam War, he served five years in the Army, including as a staff officer at the Pentagon. He retired from the military in 1971.

In later years, Wheeler, as special assistant to the Secretary of the Air Force at the Pentagon during the George W. Bush administration, helped develop the Air Force Cyber Command. A citation for his service in 2008 said Wheeler recognized that the military needed to combat the growing vulnerability of U.S. weapon systems to cyber intrusions, according to his biography.

Longtime friend and fellow West Point graduate Richard Radez said that in an e-mail the day after Christmas, Wheeler wrote he believed the nation wasn’t sufficiently prepared for cyber warfare.

“This was something that had preoccupied him over the last couple of years,” Radez said.

Wheeler’s house in New Castle was dark Monday night and no one answered the door. Yellow police evidence tape was stretched across two wooden chairs in the kitchen, where several wooden floorboards were missing.

According to The News Journal of Wilmington, Ron Roark, who has lived next door to Wheeler for seven months, said Monday he had met Wheeler only once and rarely saw him. But for four days around Christmas, he said he and his family heard a loud television in Wheeler’s home that was constantly on, but no one appeared to be home.

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

Though the police have searched the home, it is not considered a crime scene, Farrall said.

In New York City, a doorman at the building where Wheeler and Klyce shared a condominium said he hadn’t seen Klyce in two weeks and a package for her had been at the front desk for days. He said two detectives were at the condo in the Harlem section of the city.

New York City police said they couldn’t immediately confirm that they were involved in the investigation. Telephone messages left for Klyce at the New Castle home were not immediately returned.

Wheeler spent much of his post-Army career in Washington, D.C. For eight years from 1978 to 1986, he was special counsel to the chairman of the Securities and Exchange Commission.

During those years, he also created the Vietnam Veterans Leadership Program for President Ronald Reagan and was chairman of the Vietnam Veterans Memorial Fund that helped get the wall built. It is one of the most popular monuments in Washington, D.C.

Fund founder and president Jan Scruggs said Wheeler dedicated himself to ensuring that service members were given respect.

“I know how passionate he was about honoring all who serve their nation, and especially those who made the ultimate sacrifice,” Scruggs said in a statement.

James Fallows, a national correspondent for The Atlantic magazine, says he had known Wheeler since the early 1980s, and wrote on the magazine’s website that Wheeler spent much of his life trying to address “what he called the ’40-year open wound’ of Vietnam-era soldiers being spurned by the society that sent them to war.”

Wheeler was recently a consultant for The Mitre Corporation, a nonprofit based in Bedford, Mass., and McLean, Va., that operates federally funded research and development centers.

Wheeler’s military career included serving in the office of the Secretary of Defense and writing a manual on the effectiveness of biological and chemical weapons. He earned a master’s at Harvard Business School and a law degree from Yale, according to his biography.

He also was the second chairman and chief executive officer of Mothers Against Drunk Driving.

“He was just not the sort of person who would wind up in a landfill,” said Bayard Marin, an attorney who was representing Wheeler and Klyce in a legal dispute with a couple wanting to build a home near theirs in the historic district.

Robert Meadus, 85, who lives near Wheeler’s New Castle home, described the death as “exceedingly weird.”

“The more you think about it, the more implausible it becomes. … It’s a Perry Mason thing for sure.”