Police say a mother in western Arkansas may have used ant poison to kill her three young children.

They found four cups near the poison and a letter in Spanish saying the mother could not live without their father.

Eleazar Paula Mendez, 43, pleaded not guilty to three counts of murder on Monday.

She tells investigators that she attempted to commit suicide on Friday by swallowing ant poison, confirms prosecutor Tom Cooper. She says the children asked her to kill them too after seeing her take the poison.

"I blessed them and then I suffocated them," Mendez says, according to Cooper.

The children's father, Arturo Morales, says Mendez "was always a loving and caring mother."

"I love my wife, feel sorry for her and [am] confused by her behavior," Morales says in a statement read by a Catholic pastor. "I'd like to have the freedom to bury my children, and help Paula in any way possible."

The bodies of 7-year-old Elvis and 5-year-old twins Samantha and Samuel were sent to a crime lab for autopsies.