Ghost Case

Patrolman Jones needs some nursing after being shot on duty.
Detective Rage has a murder of a maid in the old, old money area of Delridge in Seattle. The case has her stimmed. Researching the old case files, she finds two other murders 23 years apart on the same day of the month at the Andover mansion.
Jones is home recovering and uses his computer to find another murder in 1881, same day of the month from newspaper files. This was the year the Andover mansion was being built.
How many more murders are hidden in the old, dusty files? Do they follow the 23-year cycle, and all be on the same day? Will Jones be able to tie the victims altogether where none are Andover family members. But first he suggests a ghost or a curse on the house.
Will any judge permit Rage to dig up all the victims and the old Andover members to test for DNA?