Testimony ends in case of slain social worker

? Prosecutors rested their case Thursday against a man accused of using a knife and a chain saw to kill his mental health caseworker, and the defense rested without calling any witnesses.

Closing arguments in the first-degree murder trial of Andrew R. Ellmaker, 20, were set to begin this morning in Johnson County District Court.

In a taped interview with a detective, Ellmaker, of Overland Park, admitted killing Teri Lea Zenner, 26, but did not say why. Jurors heard that tape Thursday.

Zenner, a Kansas University graduate student who worked for the Johnson County Mental Health Center, was visiting Ellmaker at his home when she was killed in August 2004.

Also Thursday, an emergency room physician testified that Ellmaker told him he killed Zenner.