A 13-year-old Georgia boy reported missing four years ago was reunited with his mother after police found him in a hidden garage compartment in his father’s home, police said.

The boy used a secret smartphone app to contact his mother via text, ABC News reports. Police visited the home and interviewed its occupants but left empty-handed until the boy sent a second message describing his exact location. He was discovered in an insulation area above the garage, behind a fake wall concealed by a linen closet.

“We opened the compartment where he was,” Clayton County Police Sgt. Joanna Southerland said. “I saw him and asked him to come forward, and he was horrified. He was frozen with fear.”

The boy was reported missing four years ago after visiting with his father, Gregory Jean. Jean and his girlfriend, Samantha Davis, and three other juveniles were arrested after police found the boy on Saturday.

[ABC]

Write to Nolan Feeney at nolan.feeney@time.com.