Police are still searching for missing 15-year-old Logan Mott, who is now being sought as a person of interest in his grandmother's apparent death, police said.

On Friday, police believe they found the body of his grandmother, 53-year-old Kristina French, in the backyard of the Neptune Beach home where both of them were reported missing earlier this week. Police said he should be considered armed and dangerous.

Police say the boy’s father, Eric Mott, returned from vacation on Wednesday to find his son and his mother missing, and his Neptune Beach house ransacked.

The father, a veteran’s corrections officer with the JSO, reported several guns were also missing from the home.

Police say they found signs of foul play, as well as French's car -- a silver Dodge Dart with a Florida tag DLLT42 -- missing.

They subsequently discovered a gravesite at the Seagate address.

Police investigators have been at the home for the last few days, along with a mobile crime lab.

On Friday, authorities excavated the grave and discovered a body that matched the description of French. However, police said they are waiting on the autopsy to confirm the body's identity.

Police said Logan Mott remains missing and they believe he is still alive. JSO said they have video surveillance from south central Pennsylvania of a person matching his description, in a car similar to the missing Dart.

Logan Mott is considered a person of interest in the case. Police stopped short of calling him a suspect, but said in a press conference Friday "we need to talk to him about what happened in the house."

Logan Mott's mother, Carrie Campbell-Mott, told First Coast News that the boy has had some has had trouble adjusting in recent months after transferring away from his friends at Fletcher Middle School and entering Sandalwood High School.

She raised concerns in recent days that the diabetic teen might not have access to his needed insulin. Police now think he has packed enough insulin packs to last him several weeks.

In an emotional Facebook post Friday morning, Campbell-Mott pleaded for her son's safe return.

Following the JSO press conference announcing the discovery of the body, she wrote:

"It is already being reported that a female body has been found buried on the property. They have not confirmed if it is Kristina but they believe it is her. The detective says they have not found Logan and they have no idea what has happened.

We need to locate Logan immediately.

Please be respectful of us at this point. Please do not give out our local address. We have small children in our home and we are devastated so please give us space."

Police advise anyone who sees Logan Mott to contact law enforcement and not to approach or interact with him.

Watch the press conference below:

Stay with First Coast News as this story develops.