Soddy Daisy Police said Jeremy Scott Ritchie admitted firing a shotgun at a trailer on Sunday morning.
His former girlfriend, Crystal Perry Ostrum, 40, was killed. Her new husband and another person were injured.
Ritchie, 39, of 14250 May Road, was taken into custody after the shooting at the Mimosa Trailer Park on Dayton Pike. He faces criminal homicide charges.
It happened shortly before 6 a.m.
Hamilton County EMS took all three victims to Erlanger Hospital.
Police said a gold van was seen leaving the trailer park. Ritchie and the van were later located in Van Buren County.
He initially did not want to talk to police, then he gave a statement.
He is being held without bond.