CHICAGO (CBS) — The son of a Waukegan couple charged with confining their 10-year-old daughter in their basement for a year is defending his parents, saying they were doing the right thing to protect the rest of their family.

Randy and Katherine Swopes were arrested on July 17, charged with unlawful restraint and child endangerment. Police and prosecutors said they kept their 10-year-old daughter locked in the basement, believing she was possessed by a demon.

Their 21-year-old son said his parents don’t deserve to be behind bars. He said his parents felt the 10-year-old was threatening the rest of the family; that she had written letters and threatened to kill the rest of the family.

He acknowledged his 10-year-old sister was forced to stay in the basement most of the time, slept on a cot, was made to use a portable potty training toilet, and was forced to use a bucket to shower.

Randy, 48, and Katherine, 49, have faced child abuse allegations before.

The Illinois Department of Children and Family Services said they have had at least five encounters with the family since the 1990s.

DCFS first had contact with the couple in 1994 in downstate Illinois. They underwent five months of counseling for abuse allegations regarding two of their three children.

In 2006, the family was investigated for medical neglect for refusing treatment for their son based on religious reasons.

Two years later, the family again was investigated for refusing medical treatment for their children for religious reasons. Randy Swopes allegedly used thread and glue to stitch the wound of his 14-year-old son, resulting from a health condition. He was charged with aggravated battery, and later agreed to a plea deal that sentenced him to 24 months of probation and 250 hours of public service.

All eight of their children at the time were placed in foster care for “medical neglect and physical abuse.”

By 2011, the couple had completed reunification counseling, passed both supervised and unsupervised visits, and were granted the return of their five youngest children. The three oldest, ages 16 to 19, chose to remain in foster care.

Following last week’s arrests, the couple’s daughter and three other children, ages 7, 13, and 15, were all placed in foster care.

Bond was set at $750,000 for Randy Swopes and $150,000 for Katherine Swopes. Both remain in jail in Lake County.

They were due to appear in court on July 31.