The prominent retired Army officer whose body was found in a Delaware landfill on New Year's Eve was spotted near a building that includes federal offices in Wilmington before his death, police said this morning.

The announcement came as an FBI spokesman said the bureau planned to "offer technical assistance" in the homicide investigation of John Parsons Wheeler 3d.

The spokesman, Rich Wolf, declined to elaborate. In FBI parlance, the term "technical assistance" often refers to forensic assistance, and does not mean the FBI is conducting a full investigation.

Wheeler, a driving force behind the Vietnam Veterans Memorial in Washington and former senior Pentagon official, was found dead on New Year's Eve in a landfill a few miles from his New Castle home.

On Dec. 28, Wheeler, 66, was scheduled to take an Amtrak train from his consulting job with a defense contractor, Miter Corp., outside Washington, to the Wilmington stop. His body was discovered in the landfill three days later.

This morning, the police announced that he had been spotted about 3 p.m. Dec. 30 near 10th and Orange Streets in Wilmington, a block that includes the offices of the U.S. Attorney and Justice Department. The police statement did not say how he was spotted or if he was traveling with anyone. Police were not immediately available to comment.

Police ruled the case a homicide but would not say whether they had determined how Wheeler died.

"It's a total, total shock - beyond the pale for a community like New Castle," said Bayard Marin, a local lawyer who was representing Wheeler in a neighborhood land dispute. "I exchanged e-mails with him that afternoon, and it was all very routine. Nothing suspicious at all."

The killing drew national attention Monday because of the mysterious circumstances and because of the positions Wheeler had held in the nation's capital.

In addition to helping launch MADD and leading the organization that built the Vietnam Veterans Memorial, Wheeler worked for the Securities and Exchange Commission on investigations of illegal insider trading and for the Pentagon on cutting-edge issues.

From 2005 to 2008, Wheeler was a special assistant to the secretary of the Air Force, and he helped create the Air Force Cyber Command.

A graduate of Harvard Business School and Yale Law School as well as West Point, Wheeler created a Vietnam veterans job program for the administration of President Ronald Reagan and the Earth Conservation Corps for at-risk youth for the administration of President George H.W. Bush.

"Jack used his institutional pedigree to fight for causes that mattered to him," said his friend James Fallows, an author and writer for the Atlantic magazine.

Wheeler was "a complicated guy, emotional, but someone who really cared about doing the right thing," said Fallows, adding he worked with him on Wheeler's 1984 book, Touched With Fire: The Future of the Vietnam Generation.

Wheeler was profiled with other Vietnam veterans in Rick Atkinson's 1989 book, The Long Gray Line: The American Journey of West Point's Class of 1966.

Voted "most likely to succeed" his senior year in high school, Wheeler gave up a scholarship offer from Yale, his mother's choice, and picked West Point, where his father had matriculated.

"A few cadets - Jack Wheeler among them - had doubts about this war," Atkinson wrote, "but they prudently kept their questions to themselves." After the war, Wheeler said "Vietnam reminded him of a huge trampoline with a half-million Americans bouncing around on it uncontrollably."

He nevertheless stayed true to the military, Atkinson wrote. Wheeler framed an epigram a West Point instructor had given him: "War is my business; business is good."

After serving in Vietnam, Wheeler worked at the Pentagon producing and analyzing nuclear-war games. According to Atkinson's book, Wheeler wrote a study that played a role in President Richard M. Nixon's 1969 decision to renounce biological weapons.

When it came time to leave the Army, Atkinson wrote, Wheeler asked friends and family these questions: "What's best for the Army? What's best for the country?"

It was a philosophy, neighbors said Monday, that he brought to New Castle five years ago.

Despite Wheeler's impressive resume and regular commute from small-town New Castle to big-city Washington, neighbors remembered him as considerate and humble.

"Whenever we went to a restaurant, he was the kind of guy who always found out about the server's background and asked how business was going," said neighbor Robert Dill.

Dill said he mentioned to Wheeler recently that one of his sons was fascinated with the giant military transport planes known as C-5s. Wheeler arranged for a tour at a base. "You would have thought the president was with us," Dill said of the reception he and his sons and grandchildren received.

It was Wheeler's passion for history, neighbors said, that put him and his wife, the textile executive Katherine Klyce, at odds with a couple building a home across from his three-story red brick duplex in a historic part of New Castle. The new home was too large for the location and would block views, the Wheelers argued in a court filing.

Marin, the lawyer for the Wheelers, said he doubted the dispute was related to Wheeler's death. "There's always hard feelings about the other side in a case like this, but there was never any personal animosity," he said.

Still, he said he hoped federal authorities become involved in the case, given Wheeler's long connection to the federal government.

Newark Police Lt. Mark A. Farrall said his department was seeking information on Wheeler's whereabouts from Dec. 28 through 31. He said an autopsy showed "the body was not in the Dumpster for a long period of time."

Police in Wilmington went to the Cherry Island Landfill at 9:56 a.m. Friday for a report of a body being dumped from a Waste Management refuse truck. Investigators determined that the truck had made numerous pickups in Newark, starting at 4:20 a.m.

Police said the body's location suggested it had been picked up early in the route.

Anyone with information is being asked to contact Newark Detective Nicholas Sansone at 302-366-7110, Ext. 135.

The Wheeler family issued a statement Monday requesting privacy and declining interview requests: "This is a tragic time. . . . We are grieving our loss."