Earlier this week, the mother of the missing teen, Carrie Campbell-Mott, issued a plea to the public for the pair's safe return on social media and a Florida Missing Child Alert was issued for Mott on Tuesday.
The teen, who police have identified as Logan Tyler Mott, was last seen Thursday in central Pennsylvania, according to reports from news organizations in Florida.
Campbell-Mott says her son is insulin-dependent and was anxious he wouldn't survive, but deputies said Friday they believe he has his insulin pump with him.
He is 5 feet 9 inches tall, 120 pounds, and has blonde hair and brown eyes. French is described as being 5 feet 4 inches tall with blond hair and light-colored eyes.
Missing child alert issued for 15-year-old Duval County boy
The two may be in a silver four-door Dodge Dart with Florida tag DLLT42, according to the JSO. She also said that Logan and French were supposed to pick up his father and his girlfriend from the airport, but never arrived and attempts to contact them have failed.
Neptune Beach Police and the Jacksonville Sheriff's Office, where Mott's father works as a corrections officer, launched an investigation.
Police said firearms are also missing from a home associated with the two, so do not approach them or the vehicle, if encountered.
Lendvay said investigators now believe he is in possession of his insulin packs.