Police in Newark, Del., have recovered John Wheeler's cell phone in the house under construction across the street from Wheeler's home in New Castle. Del., reported ABC affiliate WPVI in Philadelphia.
The ex-presidential appointee had filed a lawsuit, challenging the zoning approval for the neighboring house because it partially blocked his view of Battery Park and the Delaware River.
Police have been looking into the possibility that Wheeler may have set off smoke bombs in the house earlier last week.
Wheeler reportedly fought with a neighbor over the construction of the home. An attorney for that neighbor issued a statement saying his client was saddened by Wheeler's death.
Authorities have also interviewed a cab driver after finding his phone number on Wheeler's cell phone.
The driver, Athel Scott, said he doesn't know how his number got on Wheeler's phone, but he said he does remember seeing him.
"I seen him one day by the Hotel duPont and one day I seen him at the train station going inside that little store, that's all I know," Scott said.
Police also announced Friday they have uncovered more surveillance video from the night Wheeler was last seen alive. The video shows Wheeler leaving the Nemours Building in Wilmington, then walking down the street, passing through the Hotel duPont valet parking area further, before crossing over to Market Street.
In one portion of the video, the 66-year-old Wheeler appears confused as he held a shoe in one hand, and limping slightly. He is last seen on camera at 8:42 p.m. on Dec. 30.
Former homicide investigator Brad Garrett told ABC News, "So the, the question for investigators is, does it all really go together or is it pieces? When I say pieces, did he have a stroke, for example? Becomes disoriented, he wanders around. He hits into the wrong crowd. They kill him. They rob him, whatever they might do."
Wheeler's death remains a distressing mystery for his family and the police.
Investigators are continuing their efforts to talk to Wheeler's friends and associates, and are asking for the public's help. Meanwhile, Wheeler's family issued a statement today, thanking the police for their efforts:
"The family of John P. Wheeler III is most grateful for the efforts of the law enforcement authorities in the ongoing investigation into his death. The family is sincerely thankful for all the personal expressions of sympathy and condolences received from so many whose lives were touched by Jack in such positive ways. We reiterate our previous requests for privacy as we mourn his loss and ask that our decision to refrain from further comment at this time be respected."
Wheeler, a former presidential appointee and defense consultant, was found dead as his body was being dumped out of a dumpster into a Wilmington, Del. landfill on New Year's Eve.
Police said they still don't know some basic facts in the case, like where and when Wheeler was killed. They are investigating the case as a homicide.
Police traced the route of the garbage truck that dumped Wheeler's body, and discovered the truck's pickup route was in nearby Newark.