Wheeler, 66, was found dead in a Newark, Del., landfill on the morning of Dec. 31. An autopsy revealed the former Pentagon aide's death was a homicide, police said, although they have not commented on any details of how he might have been killed or what his killer's motive might have been.
Police think that at some point in the hours leading up to the discovery of his body, Wheeler came into contact with the person or people responsible for taking his life. In order to narrow down the pool, which could include thousands of potential suspects in a city with a population of more than 30,000, investigators are looking at the timeline of events that led up to Wheeler's homicide.
This is what they know right now:
Dec. 25 -- Wheeler's neighbor reportedly took him to the Wilmington train station. He was to ride the train to New York City to deliver a present to his wife, who was staying at their Manhattan condominium, and then go to Washington, the neighbor told the Philadelphia Inquirer.
Dec. 28 -- After working at his consulting job at Mitre Corp., in McLean, Va., Wheeler made a reservation on an Amtrak train from Washington to Wilmington. Authorities think Wheeler was on the train but have yet to confirm it.
The state fire marshal is still investigating the smoke bombing, police said. They have yet to name a suspect or person of interest.
Dec. 29 -- About 6 p.m., a disheveled Wheeler showed up at a drug store in New Castle that he had previously frequented and asked the pharmacist, Murali Gouro, for a ride to Wilmington. Gouro apparently declined and instead offered to call a cab. Wheeler declined and left the store, police said.
"He looked a little different," Gouro later told the News Journal of Wilmington.
Roughly 40 minutes later, a dirty and disorientated Wheeler was caught on video surveillance inside the parking garage at the New Castle County Courthouse. He was carrying one shoe in his hand and told the parking garage attendant, Iman Goldsborough, that his briefcase containing his parking ticket had been stolen and he could not find his car.
"He didn't look good to me," Goldsborough told Fox News. "He seemed like he was kind of confused. ... To me, it seemed like he was almost suffering from dementia or something."
Wheeler wandered around the garage for a few more minutes and then disappeared, Goldsborough said.
Dec. 30 -- Video surveillance captured Wheeler inside the Nemours Building, at 10th and Orange streets in Wilmington, from 3:30 to 8:30 p.m.
"On this video, Mr. Wheeler appears confused. ... Mr. Wheeler was approached inside this building by several individuals who offered assistance to him, which Mr. Wheeler declined," the Newark Police Department said in a press release.
Dec. 31 -- At 9:56 a.m., authorities were called to the Cherry Island Landfill after a worker saw Wheeler's body fall out of a trash truck that was dumping its load.
"Based on information learned during the autopsy, it is believed that the body was not in the dumpster for a long period of time. ... The first pickup of a dumpster was at 4:20 a.m. ... Due to the body's position/location in the refuse truck, it appears that the dumpster [containing his body] was emptied at the beginning of the route," police said in a press release.
Roughly 14 hours passed between the time Wheeler was last seen and the discovery of his body at the garbage dump.
Authorities would like to continue narrowing the timeline of events in the case and are asking anyone who may have seen Wheeler after 8:30 p.m. Dec. 30 to contact them. Someone who had contact with Wheeler during that time might hold the key to unlocking the mystery of his death.