Just a few blocks away, detectives were still keeping surveillance on Richard Corpus and waiting for his DNA results from the lab. But in early January police got the news: Richard Corpus' DNA was not a match.
That startling development moved Jarred Harrell to the top of the list of suspects. Investigators set out to get his DNA for laboratory testing. Then, suddenly, Harrell vanished. Investigators say he went to Meridian, Miss., and moved in with his aunt, who in Web posts proclaimed herself an "artist of the macabre" and exhibited a fascination for death, tortured bodies and mutilation.
Police tracked Harrell's new whereabouts and by February had enough information to take action. Harrell was officially arrested on 29 counts of child pornography -- but also was named a person-of-interest in the Somer Thompson case. Police then searched Harrell's various places of residence, including the house on Gano Avenue, in hopes of finding evidence to link him to Somer's murder.
Police teams worked late into the night, while two houses away, Richard Corpus -- the man who police had suspected early on -- was breathing a sigh of relief.
"To tell you quite honestly, if, if I didn't have a family, I'd probably be dead," said Corpus. "I probably would've killed myself around Christmas. Because that's how deep it got to me. Because I couldn't clear my name."
Police said on Harrell's camera they found explicit photos and a video of a 3-year-old whom Harrell knew. Harrell was charged with 26 more counts, including molestation and photographing sex acts.
Given the evidence against Harrell, some Orange Park residents wondered what took the police so long to get him off the street. They had Harrell's computer back in August -- why was he still living on Gano Avenue in October, when Somer disappeared?
Tami Loehrs is a computer forensics expert who has worked on several high-profile cases involving child porn.
"Of course he could have been off the streets," Loehrs said.
Loehrs said the fact that Harrell might have known at least one of his victims should have been an immediate red flag.
"That is probable cause in all of the cases I have seen," Loehrs said. "That was enough to go in and get a search warrant so that they could do a forensic preview."
Police issued a statement saying they followed protocol. The process took so long, they said, because authorities had to first determine that the child porn did, in fact, belong to Harrell.
Months earlier, before she knew who would be charged, Diena Thompson told "20/20" she wanted to meet her daughter's killer face-to-face.
For the rest of the Somer Thompson story, watch "20/20" Friday at 10 p.m. ET