Rose Marie Sowders, 33, Bloomington, is facing three counts of murder in Monroe County.
According to the Monroe County Sheriff's Department, on Friday morning shortly after midnight, it received word of gunshots at a duplex a mile south of Bloomington.
When police arrived they found the lifeless bodies of Eric Sipes, 34, and his 10-year-old son, Derrick, in Eric's bedroom.
Witnesses told police they saw Sowders' car leave the residence after the shots.
"Sowders and Sipes were in a relationship that may have been coming to an end," deputies reported.
After leaving the Sipes residence, police believe Sowders drove to the home of her ex-husband, Jeff Rainbolt on Garrison Chapel Road and shot and killed him. She got the couple's 2-year-old son and drove to her brother's residence near Henricksville in eastern Greene County.
According to police, she told her brother she had shot her ex-husband and boyfriend.
The brother went to a neighbor, Greene County Sheriff's Deputy Randy Frye, and reported the information to him.
Monroe County investigators were at the Sipes residence when they learned of the shooting of Rainbolt. Deputies responded to the residence and found Rainbolt in the kitchen.
Monroe County authorities drove to Greene County and took Sowders into custody.
She remains in the Monroe County Jail without bond.