A Butler man responsible for the fractured skull of his girlfriend's 9-month-old daughter could spend as little as 30 days in prison.

"I'm pissed," said the victim's grandmother, Michelle Milesend of Butler. "He could have murdered my granddaughter."

Court records say defendant Matthew Gene Blumling, 24, was watching the baby, Karmin, when the injury occurred Jan. 9.

Investigators were alerted by hospital officials, who also treated Karmin for a broken leg and arm.

Milesend said some of the injuries were showing signs of healing, and likely occurred over a period of weeks.

The baby's mother, Jessica Hough, told investigators her daughter's head injury occurred after she'd gone to work Jan. 8 and left the baby in Blumling's care, according to court documents.

When questioned, Blumling reportedly cited a number of potential accidental causes for the injuries. But a child abuse expert initially said the child's injuries were not consistent with the explanations, according to court records.

Blumling was charged with multiple crimes, including a felony count of aggravated assault. But in June he pleaded guilty to misdemeanor counts of child endangerment and simple assault.

Butler County Assistant District Attorney Richard Bosco explained the circumstances of the plea offer.

He said officials could not prove exactly where, when or who the baby was with when any of the injuries occurred, except that the head injury definitely occurred the evening in question while the child was in Blumling's care.

As for the cause of that injury, Bosco said, "a number of other possibilities were raised by the defendant —- he claimed it was a trip or a drop."

Bosco said the plea offer was grounded in what prosecutors believed they could prove in court.

"The plea was based on reckless conduct by the defendant, not intent to do harm," Bosco said. "We were very specific about that."

Butler County Judge Timothy McCune sentenced Blumling to the terms of his plea arrangement: 3 to 12 months in the county prison and two years' probation.

As part of his plea arrangement, Blumling could be paroled to house arrest with electronic monitoring after serving 30 days if he is well behaved behind bars.

Bosco said he was surprised to learn Milesend was disappointed with the plea arrangement because officials from his office met with her on at least four occasions before agreeing to the deal.

Milesend agrees that she met with the prosecutors, but believed the defendant would see a year in prison.

"I thank God every day for letting her live," Milesend said of her granddaughter. "The injuries on her were unbelievable."

Karmin, now 2, has recovered from her physical injuries, Milesend said. But the little girl seems to fear men and cling to her mother a little more than the average toddler.

"We never thought Matt could have done anything like this," Milesend said. "I pray he never dates a woman who has children again."