Arrest warrant issued for Florida teen for the murder of his grandmother The body of Kristina French, 53, was found in a shallow grave Friday afternoon.

 -- An arrest warrant has been issued for a 15-year-old boy for the murder of his grandmother, the Jacksonville Sheriff's Office in Florida announced this afternoon.

The body of Kristina French, 53, was found in a shallow grave Friday afternoon in the backyard of a home belonging to her son. Her grandson, Logan Mott -- the suspect in her murder -- also lives at the home.

Mott was found Friday in Buffalo, New York, where he was taken into custody.

He will be arraigned on a murder charge Wednesday at 9:30 a.m. in Buffalo before State Supreme Court Justice Russell Buscaglia, ABC affiliate WKBW reported.

Mott's extradition hearing was supposed to take place Monday, but it was postponed until Wednesday because his attorney had a scheduling conflict, according to WKBW.

Mott "adamantly denies any involvement in his grandmother's death and he's very upset about it," Dominic Saraceno, a lawyer hired by Mott's family, told ABC News on Sunday.

Saraceno said he spoke to Mott at the Erie County Youth Services Center, the detention center where he was being held on a grand theft auto warrant.

"My understanding is he has no history of crime, he's a ninth-grade student, he's a good student, he's well-liked by his classmates. And the only type of medication that he is on is for juvenile diabetes," the lawyer said.

U.S. Customs and Border Protection (CBP) officials encountered Mott driving Friday at the Peace Bridge near the center of downtown Buffalo after he made a wrong turn onto the bridge.

The officers took him into custody without incident after a primary inspection revealed he was the subject of a warrant for grand theft auto in Florida, according to CBP public affairs liaison Aaron Bowker.