He's a former butcher who confessed to killing 8-year-old Leiby Kletzky and cutting up the boy's body. Now, Levi Aron awaits arraignment on a murder charge while detectives in two different cities try to find out why he carried out this crime, and if he is behind any others.

Investigators took DNA samples from Aron, 35, Thursday morning to compare them with genetic prints left behind at various other crime scenes, with the focus on unsolved crimes against children.

Police Commissioner Raymond Kelly also revealed Thursday, that there were a number of scratches on Aron's arms and wrists when he was placed into custody, suggesting his 8-year-old victim put up a fight before he met his fate.

"Based on marks on the defendant, it appears that there was some sort of struggle," Kelly said at the late morning press conference.

Essentially, police have two reasons to suspect that Aron is a serial killer. One, the precision with which he tried to cover up the murder. When cops raided his home Wednesday and asked Aron where the boy was, he gestured to his otherwise empty refrigerator, which had three bloody knives and a cutting board inside. They found the little boy's severed feet in separate Ziploc bags in the freezer.

Detectives say the man who most people describe as a quiet loner had also packed other parts of the boy's body into sealed plastic bags that he put into a red suitcase which he then put in a dumpster two miles away. All are signs, police say, of careful planning by a killer to cover his tracks.

Another reason detectives are investigating whether or not Aron carried out this sort of crime before is the abrupt change in his life six years ago. That's when he left his lifelong home in Brooklyn for Memphis, Tennessee after marrying a woman from there whom he'd met online.

He stayed for two years, working as a kosher butcher in a supermarket for a time and as a security guard. He remained married for only a year, and his wife ended up filing an order of protection against him. Chip Washington, a spokesman for the sheriff's office of the county in which Memphis is located, Shelby County, wrote in an email to The Commercial Appeal newspaper of Memphis, "According to our records, he appeared in court where the charges were dismissed so there is NO mug shot available. This is the ONLY record we have of him."

Not much else is known about Levi Aron's life in Memphis. Investigators from both the NYPD and Shelby County Sheriff's Office search for more details now.

Kelly confirmed that his detectives are looking into the possibility that Aron is a serial killer. However, Kelly said, "there's no reason to believe that at this time."

Kelly said that his investigators have been in contact with a variety of law enforcement agencies that Aron may have come into contact with, but there was no indication of significant foul play on Aron's part. "They don't have any record of him... no strange, unusual or illegal activities. We don't have any record of that at this time."

Another place detectives are searching is Aron's home, a third floor attic apartment in the Kensington neighborhood of Brooklyn. There were three computers in the house," Commissioner Kelly said. "That information is going to be gone through."

Back in Borough Park, Brooklyn, one of Aron's neighbors told police that he had tried to get her son into his car months ago, but she assumed Aron was trying to be helpful.

Commissioner Kelly said that even he was emotionally affected by this case, despite handling and overseeing decades of hard cases. "In this business you see a lot of violence," the commissioner said, regarding the thousands of cases he's dealt with. "There's usually some twisted logic [involved]. Here, it defies all logic. That's what's so terribly disturbing about this case."