MIAMI (CBS4) -Hours before a naked Rudy Eugene devoured nearly 75 percent of a homeless man’s face on the Miami side of the MacArthur Causeway, he spent the morning on South Beach, cruising the streets in his purple sedan and mingling with visitors in town for Urban Beach Weekend.

CBS4 News Investigative Reporter Jim DeFede was able to piece together the final twelve hours of Eugene’s life, culminating with the horrific moment Saturday afternoon when the 31-year-old turned into a growling cannibal and attacked Robert Poppo, a homeless man who frequently slept under the causeway. Eugene ripped the clothes from Poppo’s body and then the flesh from Poppo’s face before a Miami police officer finally arrived and shot Eugene to death.

Since the incident, police have been trying to learn how these two men’s lives came to intersect one another as well as what may have caused Eugene to turn into the living embodiment of Hannibal Lechter.

According to two police sources familiar with the investigation, at 2 a.m. on the day he would die Eugene was at his girlfriend’s house in Miami Gardens. She told police he seemed strange, going through his clothes and her clothes in a mania. Suddenly he announced he was going to leave, and drove to a friend’s house in NW Miami-Dade.

By 6 a.m., police said Eugene wanted his friend to come with him to Miami Beach and check the scene at Urban Beach Weekend, where 200 thousand people had gathered to party for Memorial day. When the friend said he had to work, police said Eugene went on his own.

Police now know he parked the car illegally in the area of Tenth Street and Alton Road, and then was unable to get it started so he could move it. CBS4′s sources said Eugene abandoned the car, which was later towed by Miami Beach officials, as part of their routine roundup that weekend of illegally parked cars.

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Things get fuzzier at this point. There are no details about what Eugene did after he abandoned his car, but police believe he made the decision to cross the causeway on foot, a hike of a little more than 3 miles.

It was a hot day, with temperatures in the 90′s, and a long walk. Either late that morning, or early that afternoon, police sources said, Eugene began his trek back to Miami. As he walked across the causeway, they said he started stripping, leaving his clothes on the walkway and in the road.

Cops found his drivers license and clothes strewn from the beach to the mainland.

Had he not abandoned his car, Eugene likely would have driven right past the spot along the causeway under the elevated track of the MetroMover where he met Robert Poppo about 2 p.m.

Instead, on foot, he ran into the 68 year old homeless man, who police believe he’d never seen until that moment. It was at that point that police believe Eugene set in motion the events that led to his death at the hands of police and Poppo’s gruesome mutilation.

In images captured on a security camera mounted on the Miami Herald building, you can see what appears to be Eugene, now totally naked, attempting to strip the pants off Poppo as he attacked the man.

At that point, what police know is a blank until they started to get reports of a man attacking another man. One cyclist who rode past the fight flagged down an officer, and said a naked man was biting another man.

On the same security camera, you can see the officer drive up, get out of the car, and casually walk to where the two men were fighting, obscured from the camera view by the train track. Suddenly, the officer does a double take, pulls his gun, and aims it.

The head of the Miami Fraternal order of Police said the officer saw Eugene stripping the flesh from Poppo’s face with his teeth and ordered Eugene to stop. Eugene growled at the cop and continued to eat, Aguilar said, so the officer shot him.

When the shot had no effect, Aguilar said, the officer continued to shoot until Eugene’s cannibalistic meal stopped. Eugene was dead, and Poppo was left half naked in the street, his face a ruin. He was hospitalized and, according to CBS4 sources, has been unable to tell police anything.

While police now believe they know what happened, CBS4 sources say they simply don’t know what caused Eugene to attack Poppo, and more importantly, what caused him to turn cannibal.

Eugene, a former high school football player in the late 90s who married and was divorced in 2007, is believed to have had some tough financial times.

CBS4 sources said he was autopsied over the weekend by the Miami-Dade Medical Examiner’s office, which reportedly found nothing unusual. Toxicology screens which test for drugs and chemicals in the blood and body take much longer to complete, so police don’t know if drugs played a part in his maniacal rage and descent into cannibalism.

Results could take between two weeks and two months. Until then, the mystery will linger. Police are working under the theory that Eugene was under some kind of drug-induced psychosis, but at this point, it’s just a theory.

Poppo, who has a long record of homelessness and petty crime in Miami-Dade county, has tubes in his body and cannot speak. Sources tell CBS4 there is cautious optimism he will survive, a man with no home, and now, no face.