Country singer Mindy McCready earlier this month threatened to kill herself after losing custody of her sons and yet was allowed to leave a court-ordered rehabilitation program. Then few days later was found dead in an apparent suicide at her northern Arkansas home.

Cleburne County Sheriff Maty Moss said Monday it appears McCready shot and killed her late boyfriend David Wilson's dog, before shooting herself Sunday.

Moss says McCready's official cause of death had not yet been released but treating it as a suicide. It appeared that she was home alone.

McCready had been publicly battling substance abuse and mental illness since she was on three years' probation over illegally obtaining OxyContin in 2004. She has also attempted suicide twice in 2005 and 2008.

The troubled star leaves behind two sons 6 year old Zander and 10-month-old Zayne.

"Zayne and Zander are loved, cared for and comfortable with foster families at this time," her representative told CNN.

Billy McKnight, a former longtime boyfriend and father of her oldest child, Zander, said the mother of two stayed in court-ordered substance-abuse treatment center for about 18 hours before checking out.

"That was a big mistake on the part of whoever released her," McKnight said. "... She was in a terrible state of mind. She doesn't perform any more. She wasn't working. She has two kids and her fiancé was just killed. There's no way she should be out by herself in a lonely house with nothing but booze and pills. That was a really, really bad mistake, and the end result is tragic."

McCready's sons were put in foster care and McKnight is working with authorities to get custody of his son, Zander.