"The burial site was excavated today and human remains were located". They took an Uber home from the airport Wednesday after French never showed up to get them.
At this point, JSO says 15-year-old Logan Mott is still missing, as is the silver Dodge Dart.
A surveillance camera at a gas station in south-central Pennsylvania picked up an image of Logan and the vehicle on Thanksgiving at 1:15 p.m. Ron Lendvay, a director of investigations and homeland security for the Jacksonville Sheriffs Office, told Florida Times Union.
He is now being held by the Buffalo Police Department on the auto theft warrant.
Authorities emphasized Mott is only a person of interest in the case - not a suspect - and they're looking to "talk to him about what happened at the house".
According to Jacksonville Sheriff's Office director Ron Lendvay, the Neptune Beach Police Department and the Jacksonville Sheriff's Office began an investigation and determined that "possible criminal violence" occurred inside the home.
It is the same home where police have been investigating the disappearance of teen Logan Mott and French, his grandmother.
Pakistan calls in army as Islamabad protests turn violent
The government also shut down Facebook , Twitter , and YouTube in Islamabad and Rawalpindi to block coverage of the operation. A mob attacked former Interior Minister Nisar Ali Khan's house in Rawalpindi and broke the main gate of his house.
Mott's mother confirmed with First Coast News on Friday evening that Logan has been detained, but he is safe and sound.
They were reported missing after Logan didn't show up to Sandalwood High School Monday or Tuesday.
"We are relieved he is safe and in custody and we just ask for everyone to give us time to sort out what happened", Carrie Campbell-Mott, the teen's mother, said in a statement to ABC News after her son was detained Friday.
"No matter what, Logan is our child and we love him and are standing by him to help in any way", she said.
She said a Jacksonville detective will fly to meet Logan on Saturday. Her weapons were gone, as was her Dodge Dart.
Logan's mother told via the Florida Times-Union she last spoke to her son Sunday, with the mother saying he seemed to her to be in a good mood.
Action News Jax is working to get more details and will have updates as soon as they become available.
"A big thank you to all for sharing and allowing us to quickly stop Logan Mott".