Woman 'trapped in wooden box by sex offender boyfriend' found dead alongside her son

Police are now attempting to find James B. Horn Jr., 47 who allegedly locked Sutton in a box, and is suspected to have killed the mother and son

James Barton Horn Jr., who police are searching for after finding Sandra Kay Sutton, 46, and her son, Zachary Wade Sutton shot to death at a relatives home (Missouri State Highway Patrol via AP, File)

A woman who escaped captivity from a wooden box has been found dead alongside her teenage son, as police attempt to track down her “extremely dangerous” ex-boyfriend suspected of trapping and killing her.

Sandra Kay Sutton, 46, from Missouri fled from the wooden box, where her boyfriend allegedly kept her captive, in late April.

Police have since found Ms Sutton and her son Zachary Wade Sutton, 17, fatally shot in a house in the city of Clinton, around 45 miles from where she escaped.

Officers are now attempting to find James B. Horn Jr., 47. The convicted sex offender routinely locked Sutton in a box in their home in Sedalia, Missouri, over a four-month period, the woman told police.

Horn has been at large since he was charged with kidnapping, armed criminal action and unlawful use of a weapon.

“He is a dangerous person, an extremely dangerous, violent person,” said Clinton Police Lieutenant Sonny Lynch.

The downtown area of the city where Horn and Sutton lived (Image: Dave Herholz/Creative Commons) (Dave Herholz/Creative Commons)

Sutton told police that Horn would force her into the small box before he left their home by threatening her with a long knife. Horn would then release Sutton when he returned home, and would make her have sex with him, the authorities said.

The box measured just 100 inches (2.5 meters) long, 45 inches (1.1 meter) wide and 52 inches (1.3 meter) tall, according to police documents.

On Thursday, police discovered a vehicle belonging to Sutton parked at a hospital in Sedalia near the home where he had kept Sutton captive, Lynch said.

Local police and Missouri State Highway Patrol officers stormed the house and nearby abandoned properties, but left the scene when they could not find Horn, said patrol operator April Lewis.

Zachary's high school has paid tribute to the teenager in the wake of this death.

A Facebook post by Clinton High School posted read: “We are heartbroken over the tragic and senseless loss of Zach Sutton and his mother. Counselors are available at CHS."

Horn was put on the sex offenders register after he was convictions in Tennessee in 1993, according to Missouri State Highway Patrol online court records.

He later was convicted of kidnapping his estranged wife in Mississippi and served 10 years in federal prison, court records show.

Additional reporting by Reuters