Steven Pladl, 43, killed his wife, baby, and his wife's adoptive father before taking his own life on Thursday morning in New Milford, Connecticut. Katie was both Steven's wife and his biological daughter. The pair was arrested and charged with incest earlier this year.

Read on to learn more about the case:

Four Were Killed In the Murder-Suicide

Four people were killed in the incident: Katie Pladl, her biological father Anthony Fusco, 7-month old Bennett Pladl, and Steven Pladl, who took his own life.

At this time, Steven Pladl is suspected in the death of his 7-month-old son.

Speaking to CBS' WNCN about the gun shot that left Katie and her adoptive father dead, a witness said, "Someone just went by and shot this guy in the truck." The witness said that the victim's car was stopped with the gunman pulled alongside it, shot the two, and fled.

Katie & Steven Were Charged with Incest in January

In January, Katie and Steven were arrested and charged with incest, adultery, and contributing to delinquency at their home just outside of Henrico County, Virginia.

According to CBS News, Katie's bond required that she live with her adoptive parents in New York. She was also required to stay away from Pladl.

According to CBS News, Steven and his wife at the time gave birth to Katie in 1998 and put her up for adoption. In 2016, when she was 18, she located her birth parents and began living with them. The outlet writes, "When Steven Pladl's wife found out he was in a sexual relationship with Katie and she was pregnant, they divorced and the woman contacted police."

Speaking to NBC New York, Knightdale police chief Lawrence Capps said, "We’re trying to make sense of all the factors that led up to this senseless taking of life.” He said that their understanding was that Steven traveled to Connecticut "for the specific purpose of making confrontations."

Above is the audio recording of Steven Pladl's mother calling 911. The call was made after Steven called her on Thursday morning. Steven's mother says, in the call, "My son just called me and he told me he... oh my god... he killed his baby and he's in the house."