A Hatfield man was sentenced to life in prison Thursday after a jury convicted him of beating to death his girlfriend’s 4-year-old daughter in 2016, a crime that came to light two years later when he assaulted the girl’s 8-year-old brother.

Marquis Thomas, 35, was arrested in 2019, three years after Kailee Bunrout was hospitalized with bruises, broken ribs and burst blood vessels in her eyes. She died weeks later but county officials were initially unable to determine how she sustained the injuries. They reopened the case, after her 8-year-old brother showed up at the same hospital with injuries like the ones his sister had, and told them Thomas had regularly beaten him.

Thomas was then charged with first-degree murder and assault in Kailee’s death, as well as strangulation, aggravated assault and related offenses in the boy’s beating.

During the trial this week, Montgomery County prosecutors led by First Assistant District Attorney Edward McCann Jr., argued that Kailee was a “vulnerable little girl” who was never able to report the abuse she faced at Thomas’ hands.

Thomas’ attorney, Matthew Quigg, contended that the 35-year-old, while not the children’s father, treated them like his own, and cared for them deeply. The prosecution, Quigg asserted, had not presented evidence during the three-day trial proving that Thomas was responsible for the children’s injuries.

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In an interview, McCann said he was somewhat surprised, but relieved, that jurors convicted Thomas of first-degree murder: The jury deliberated for 10 hours over two days, and seemed to struggle to reach a consensus.

“I do think the full measure of justice in this case is first-degree murder, given the horrific injuries he inflicted on this child,” McCann said, adding that Thomas “essentially let [Kailee] die” by failing to call 911. “This is a horribly tragic case.”

In his initial statement to police in September 2016, Thomas said he woke up to find the girl unresponsive and cold to the touch. He texted the girls’ mother, saying “K.B. won’t wake up,” but hadn’t called 911 by the time she had returned home minutes later. Medics arrived but couldn’t find a readable pulse on the girl.

At the hospital, child abuse specialists and doctors took note of her injuries, including burst blood vessels in her eyes, a bruise under her left eye, two healing rib fractures, and scars on her torso. During the trial, McCann presented evidence that Kailee’s heart and liver had also been damaged, and that she had suffered significant internal bleeding.

A county medical examiner ruled the manner and cause of the girl’s death as undetermined after learning that Thomas, who did not know CPR, was seen by the girl’s mother attempting to perform the live-saving technique on her. Her injuries, the medical examiner concluded, could have been caused by Thomas’ amateur efforts.

But when her 8-year-old brother was admitted to CHOP with similar injuries almost exactly two years later, he told detectives that Thomas would abuse him when his mother wasn’t home, often choking him, wrapping his arm around his neck and pushing his face into a couch cushion, according to the affidavit of probable cause for Thomas’ arrest.

Thomas showed little reaction as the verdict was read. After the sentencing by Montgomery County Court Judge William Carpenter, Quigg said his client was devastated by the outcome and plans to appeal.