DNA tests revealed that Lindsey Lowe's betrothed, Jonathan Brooks was not the father of the tragic babies.
Hendersonville Police Detective Steve Malach told how she had told him of the affair that occurred in December and early January, when he originally questioned her about the killings.
He told the court: "I asked if it was possible anybody else was the father, and she told he she had cheated on her fiancé with another guy, Jeremy Smith."
She told the investigator that that she hadn't admitted her infidelity or told her fiance about her cheating because she hadn't wanted to "disappoint him and because she didn't want to add to the stress of a family member's illness.
Malach added paternity test results showed it was more than 99.9 per cent likely that Smith was the father of the boys.
According to News Channel 5 Lowe's attorney, John Pellegrin, said after the hearing that it was the first time he and his client had heard the results of the paternity test.
As we reported here Lowe admitted to cops that she covered the mouths of the infants with her hand after giving birth on September 12 so that her parents, whom she lived with, would not hear their cries.
Her father called police two days later after discovering one of the two babies in a laundry basket in his daughter's bedroom.
The 25-year-old who is charged with two counts of first-degree murder, denies the charges.