Allegheny County Police said a convicted sex offender violated the law again by contacting a boy through Facebook and arranging meetings that led to an exchange of alcohol for sex.

According to police documents, the 14-year-old victim met Joseph Thomas through Facebook Messenger. The victim told police Thomas used the name "Austin Thompson" on the social media site and used the site to initiate conversation.

After exchanging phone numbers, the teen and 41-year-old Thomas met several times.

Police documents stated that the victim met with Thomas up to six times, and he at times provided marijuana or alcohol to the boy in exchange for sexual acts.

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"This was discovered when the young boy came home with alcohol on his breath. The alert grandmother smelled it and knew something was wrong," said Assistant Superintendent James Morton of Allegheny County police.

After detectives investigated the boy's cellphone and social media accounts, police were able to track Thomas to his home in Greene County.  Police were also able to use a description provided by the victim to identify Thomas by his real name.

Thomas was arrested on a number of charges, including violating Megan's Law.

Police fear there could be more victims. Investigators advised parents to check their children's list of friends for the name “Austin Thompson” and to contact police to report any suspicious activity.