KNIGHTDALE, N.C. (WTVD) -- New information was released Friday afternoon regarding the multi-state triple murder-suicide this week that began in Knightdale.
Police say the infant found dead in an Earlston Court home on Thursday was in the custody of his paternal grandmother.
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The child had been in the custody of his grandmother since his mother and father were arrested in January for incest.
Previous story: Father, daughter and baby they had together dead in multi-state homicide, suicide
Police said the child -- 7-month-old Bennett Pladl -- was last seen alive on Wednesday around 8 p.m.
RELATED: 911 caller on father, daughter homicide, suicide: 'He killed his wife, he killed her father'
The child's father, Steven Pladl, asked to take the child back to his home in Knightdale. He told his mother he and the baby were going to Skype Katie -- his biological daughter with whom he was having an incestuous relationship.
Shortly after midnight that night, Steven again spoke to his mother, this time telling her he was taking the baby to see Katie in New York.
Around 8:45 a.m. Thursday morning, he called his mom and told her he had just killed Katie and her adoptive father, Anthony Fusco.
Police say he also admitted to killing the child and leaving him inside the home in Knightdale.
Steven's mother then called 911, telling police what happened.
"He told me he ... oh God ... he told me killed his baby and he's in the house," she said. "His wife broke up with him over the phone yesterday and he just ... he killed his wife, he killed her father ... I can't even believe this is happening."
Police went to the Knightdale home to perform a welfare check on the infant and found him dead.
Katie and Fusco were found dead from gunshot wounds in a truck in New Milford, Connecticut.
Officials later found Steven dead of a self-inflicted gunshot across the state line in New York.
Katie was legally adopted out of state when she was born. When she turned 18, Katie reached out to Steven and her mother through social media. In August 2016, she moved in with her biological parents and their two other children.
Steven and his wife legally separated three months later, in November 2016. The wife told authorities that the month she moved out of the home Steven had been sleeping on the floor of Katie's bedroom.
The wife also said that she learned her daughter was pregnant and that Steven was the father in May 2017 after reading one of her other children's journal. She said that she contacted Steven and he admitted that Katie was pregnant with his child and that the two had plans to get married.
Warrants said the two young children were told by Steven to refer to Katie as step-mom, even though she's actually their sister.
The baby was born in September 2017.
Police: Paternal grandmother had custody of child killed in Knightdale incest case