A mother has been arrested on charges that she gave crack to her 4-year-old son to "calm him down."

Michelle R. Shelton (search), 32, of Kansas City, was arrested Thursday on a child endangerment charge. Police said the boy did not suffer any obvious injuries from taking the highly addictive drug. He remains in state custody.

Police first began investigating Shelton a year ago when officers said they saw her escorting drug users into the apartment complex where she and her son lived. Police said some residents at the complex told investigators Shelton sometimes gave the boy crack cocaine to "calm him down."

Social workers were sent to the apartment where they took hair samples from Shelton and her son to test for illegal drugs. The tests came back positive, police said.

According to court records, Shelton told detectives she found empty crack bags and drug paraphernalia throughout her home after parties her son attended. She said it was possible the child found some of the drug.