A Tennessee man has been charged with murder in the death of pregnant mother with ties to Aroostook County.

Kyanna Howes Vaughn, 23, and her husband, Robert Vaughn, 25, were shot to death Dec. 3 inside their home in Johnson City, Tennessee. Their bodies were found the next day by a friend of the family.

Kyanna Howes Vaughn was pregnant with the couple’s third child. According to a family member, she was born in Ashland and moved to Tennessee with her mother and siblings as a child.

Derrick Benjamin Sells, 33, was arrested Dec. 9 and charged with three counts of first-degree murder, three counts of felony murder, unlawful possession of a weapon, aggravated robbery and aggravated child neglect, according to the Bangor Daily News.

Sells was on probation after being charged with aggravated assault on a police officer and had previously been convicted on drug charges.

The couple’s children, who are 3 and 6 years old, witnessed the shootings but were not physically injured. They were in state custody following the shootings. Howes Vaughn’s step-father, who lives in Gorham, said that he and his wife would seek custody of the children.

Police said Sells and Robert Vaughn were friends. They're still working to determine a motive for the killings.