The mother of two children found dead in her estranged husband’s Nebraska home told The Daily Beast on Monday that she “had a gut-wrenching feeling” something terrible was going to happen.

Mary C. Nielsen spoke out hours after the children’s father, Adam L. Price, was taken into custody in California, a 25-hour drive from his house, following a daylong manhunt.

Price was later charged with two counts of felony child abuse resulting in death. Police have not released a cause of death for 3-year-old Theodore and his 5-year-old sister Emily but said it was “suspicious.”

Their deaths came as Nielsen and Price were locked in a bitter battle over the kids.

“We were fighting for custody in court. I’ve spent every penny I have to try and get custody of my babies full time,” Nielsen told The Daily Beast, saying that Price had been “abusive and manipulative” to her during their relationship.

“The only thing that people need to know about him is that he’s a fucking monster.”

The children were on a weeklong visit with their father and were supposed to check in daily by FaceTime. Nielsen last spoke with them Thursday night.

On Saturday night, after being unable to reach them for two days, she called police in Bellevue, Nebraska, to check Price’s home. Officers went out before 10 p.m., and the next day around 9 a.m. “but did not observe exigent circumstances that would allow them to force entry into the home,” Capt. Andy Jashinske said in statement.

By Sunday morning, the situation “still was not sitting right with me,” said Nielsen. “I had a bad feeling in my stomach.”

She called a friend to go check, and that person found the kids’ bodies were in their beds. The cause of death has not been released.

“Our old neighbor actually saw Adam packing up all his stuff Thursday night,” Nielsen said. “It was kind of suspicious because he said he was going for a long weekend. The police said most of his clothes were gone. He took his personal computer but he had left his cell phone at the house.”

She described her two children as “bright and so giving.” Emily was wise beyond her years, said Nielsen. Theodore was “a mama’s boy, he just wanted to constantly be held and loved.”

In a Facebook post, Nielsen bid a heart-wrenching goodbye to her kids.

“I’m so sorry to see you two go. You did not deserve this and I love you so very much. I would fight a thousand fights to have you back again,” she wrote.

“Heaven gained two beautiful angels and I hope great grandpa was at the gates to greet you. You were the only reasons I survived everything I did and the only reason I am alive. I love you. Til we meet again my sweet babies.”

A relative set up a GoFundMe to help with funeral expenses. “Emi and Teddy were some of the sweetest most loving children and did not deserve to leave the earth this way,” the post read.