Jo Ann Bain Update: Bodies of missing Tenn. mom and daughter Adrienne found; 2 other girls still missing, FBI says

(CBS/AP) GUNTOWN, Miss. - The search for Adam Mayes, the 35-year-old family friend accused of abducting a Tennessee mother and her three daughters, has intensified after police said the bodies of Jo Ann Bain and her oldest daughter were found dead in north Mississippi.

Pictures: Tenn. mom, 3 daughters missing

Mayes was at the Bains' house helping them pack to move to Arizona when the mother and her three daughters vanished April 27, authorities said. The bodies of Bain and her 14-year-old daughter, Adrienne, were discovered late last week behind a house belonging to Mayes. The FBI did not say how the two died.

Meanwhile, the FBI said it believed the other daughters, 12-year-old Alexandria and 8-year-old Kyliyah, are still with Mayes.

FBI agents in green camouflage, carrying high-powered rifles joined K-9 units and SWAT teams in a search of the woods and back roads of north Mississippi near Mayes' home. State troopers stopped vehicles and looked in trunks Monday, and FBI agents searched the yard of a home in rural Union County.

Mayes was last seen a week ago in Guntown, which is 80 miles south of the Bain family's home in Whiteville, Tenn.

Siskovic said authorities talked to Mayes early on in the investigation, but he fled when they tried to contact him again. The search for Mayes, considered to be armed and dangerous, will be a 24-hour effort, said Jimmy Edwards, sheriff of Union County. The area has a mix of heavy woods and farmland, and is crisscrossed by two-lane back roads.