MAGNA, Utah — Police say they believe a 41-year-old woman and her 9-year-old daughter killed in a murder-suicide have been dead for at least a week.

Unified Police Lt. Brian Lohrke said at a news conference Monday night that investigators believe 41-year-old Karina Clark killed 9-year-old Madison Clark before shooting herself between one and three weeks ago.

Their bodies were found inside their Magna home on Christmas Eve after someone reported a Christmas present left on the home’s doorstep had not moved.

Lohrke says investigators are still trying to determine a motive.