A 4-year-old boy who police said was abducted from his Montgomery County home five months ago was found in Florida after an anonymous caller tipped off police. The boy's paternal grandmother was arrested in connection with his kidnapping.

Pinellas County authorities found Matthew Burns of Gaithersburg on Friday, living in the St. Petersburg area of Florida with his grandmother Cynthia Sargent.

Sargent, 45, was being held yesterday without bond pending extradition to Maryland, where she faces a felony kidnapping charge.

A spokeswoman for the Pinellas County Sheriff's Department said Sargent told police she took the child Jan. 30 because she feared that his mother was mentally unstable and that the child was in danger. The boy's mother, Jennifer A. Burns, died in May in what has been preliminarily ruled a suicide.

The boy's case was profiled on the Web site of the National Center for Missing and Exploited Children, which Montgomery police said led to his discovery. They said an anonymous caller who had seen Matthew's picture told them where Matthew was in St. Petersburg. Sargent and her husband were staying at a friend's house with the boy, police said.

"Detectives received a tip from someone concerned about this child, and that led to the recovery of Matthew safe and unharmed," said Joyce Utter, a Montgomery County police spokeswoman.

Sargent turned the boy over to authorities after police in Florida contacted her.

Matthew was reported in good condition and placed in the custody of child protective services. Florida authorities contacted his maternal grandmother, Mary Middledorf, who said she hopes to win full guardianship of the boy. She said a hearing will be held tomorrow to determine guardianship in Maryland.

Middledorf, of Laurel, disputed any suggestion that her daughter was a danger to the boy.

"She was an excellent mother. She was very good with Matthew. She was very capable of taking care of her child," Middledorf said.

She said she believes that her daughter took her own life and that Matthew's disappearance contributed to the suicide.

"She was very depressed. She had postpartum depression, but after the kidnapping she became very depressed. After four months she lost hope that Matthew would come home," Middledorf said.

Sargent and Matthew's father, Cory Wharton, went to Matthew's preschool Jan. 30 to pick him up for a scheduled visit, Middledorf said. When Wharton couldn't produce identification as required by the court, the school called Matthew's mother, who went to the school and got into an argument with the father and Sargent, Middledorf said. She said Jan. 30 was the last time her daughter saw the boy.

Matthew's father lives in Delaware and could not be reached for comment yesterday.

After the incident at the preschool, Burns complained to police that the terms of the court-ordered visitation agreement were not being obeyed. Burns told police that when she went to Sargent's home in Delaware looking for Matthew, she couldn't find him, and it appeared that the house had been vacated.

Burns was reported missing May 26. The next day, her body was found at the bottom of a cliff in the Blue Ridge Mountains in Cascade, Md. Cpl. Christopher Howard of the Washington County Sheriff's Department said police noticed a car abandoned near a military site in the area, and "when we ran the tag, we found out that a missing report had been filed."

The state police canine unit was called to help find Burns. "There is big cliff out there on the side of a mountain. She was found at the bottom of the ravine. It is a pretty serious drop," Howard said. "We are waiting for the autopsy reports but it has preliminarily been classified as a suicide."

Burns was 24.

Staff researcher Don Pohlman contributed to this report.

Cynthia Sargent faces felony kidnapping charges in Maryland.An anonymous phone call led police to Matthew Burns, 4.