MADISON, Wis. (AP) -- Dane County supervisors have approved an external review of emergency 911 operations following a mishandled call from a woman who was later killed.

The county board's executive committee heard from a number of speakers Wednesday who demanded answers to questions raised after Brittany Zimmerman was murdered in April.

County officials have said a dispatcher failed to return a call from Zimmerman's phone around the time she was killed in her Madison apartment.

The external review will include an evaluation of call data and technology as well as an assessment of training procedures.