JACKSONVILLE, Fla. -

It's been four days since a Jacksonville teenager was gunned down outside a community center pool off Division Street.

Jacksonville police aren't commenting on what they have called the gang-related shooting of 14-year-old James Thomas, but a former Jacksonville Sheriff's Office detective says Facebook and Twitter could lead detectives to key evidence in the case.

Thomas' family and friends are on social media sites, but there are other posts about the murder that could be clues detectives can follow to find the killer.

"All this Facebook violence, beefing... they need to stop it out," said Da'vonna Allen, a friend of Thomas.

A friend acknowledges there was an ongoing Facebook feud between Thomas (pictured below), his friends, and a rival group. On Thomas' Facebook page we found pictures of guns, drugs and even promises of retaliation.

James Thomas A former detective says investigators working the case, might be interested in some of those posts.

"People are thinking they are doing it and may not think people will find out who they are," said Michael Knox, a former JSO detective who is now a forensic consultant. "You might be surprised to see law enforcement knocking on your door one day."

Knox says Facebook has become a big help in solving crimes, providing posts, pictures and leads that would be tough to find otherwise. Knox says threats of retaliation are of particular concern.

"A lot of times that gives law enforcement officers the opportunity to know what's going to take place," Knox said. "All too often law enforcement is in a reactive position after a crime has occurred, but that can give us proactive information and show that there’s a chance for retaliation."

Although some people think using a fictitious name online will keep them anonymous, law enforcement agencies can subpoena Facebook to obtain their real identity. 

Knox said even pictures of guns can get teenagers into trouble and link them to a crime.

"If you have evidence that the person is engaged in any illegal activity, that can be a reason for arrest," said Knox.

Not only can information gathered on social media lead to an arrest, it often holds up in court and contributes to obtaining a conviction.