It appears that the "girlfriend" is also the mother, though it's not especially clear.
Yet another case where a "frustrated" father, possibly with a violent and/or criminal record as a juvenile, is drafted to do infant caretaking--with the usual disastrous results.
Dad is identified as TYLER RYAN GEARY.
http://www.davisclipper.com/view/full_story/23578275/article-Man-arrested-for-allegedly-shaking-baby-daugher?instance=home_news_1st_left
Man arrested for allegedly shaking baby daugher
Sep 10, 2013
LAYTON — An 11-month-old girl is in critical condition at the hospital, and police believe her father shook her in frustration and caused the harm.
At 6:30 a.m. on Tuesday, Sept. 10, parents Tyler Ryan Geary, 25, and his girlfriend, 20, brought the baby to the emergency room at Davis Hospital. She was unresponsive and showed signs of shaken baby syndrome, according to Layton City Police Lt. Shawn Horton.
Police later learned that Geary had been babysitting at home while his girlfriend was working and had become frustrated with the child’s crying. After shaking the baby, he threw her on the bed, police believe.
“It’s very sad, and we as parents have all been through a time when our babies cry and cry and we feel like there’s nothing we can do for them and so we really feel for them,” Horton said. “If you feel like yourself getting to the point where you’re frustrated, it’s time to step away for a little bit and calm down and call for some assistance. We all have someone we can call.”
Police had interactions with Geary before he was an adult, but haven’t had run-ins with him since, Horton said. The Layton man was arrested on suspicion of second-degree felony child abuse, which could be amended to a child abuse homicide charge if the baby dies.
The mother was questioned but is not a suspect in the case. She has been with her baby all day, police said.