He was engaged to be married to Pleskovic's daughter.
Scullin was arrested last week in connection to the homicide.
He was one of the people who called 911 when Melinda's body was found inside the Blazing Star Drive home in Oct. 23. He had just returned from dinner at Applebee's with Melinda's husband, Bruce. Bruce's daughter — who was engaged to Scullin — worked at the Applebee's and was working that night.
Melinda was supposed to meet the family for dinner but never arrived.
Court records show a large tactical knife was found on the back seat of a truck Scullin said he drove the day of the killing. Police said the knife had Melinda's blood on it. DNA belonging to Scullin was on the handle.
The making false alarms charge stems from an incident on Oct. 19 when he called 911 to report a break-in. The complaint states that break-in never happened.
The new endangering children charge involves Scullin's 1-year-old daughter. The indictment says Scullin "did recklessly create a substantial risk to the health and safety" of the girl by "violating a duty of care, protection or support."
When Scullin called 911 to report that Melinda had been "attacked" he said his daughter was inside the home with Melinda and the Pleskovics' nonverbal teenage son.
Prosecutors say Melinda died from multiple stab and gunshot wounds.