Despite mounting frustration for the family of an infant who suffered traumatic brain injury last month, Superior police say they are looking into the case.

Chad La Lor, captain of investigations for the Superior Police Department, confirmed there is an ongoing investigation related to an infant who was injured in Superior.

"We are investigating the case of a baby that presented at the hospital with injuries that did not appear to have occurred naturally," he said.

That is small comfort to Tracy Porter, who spends her days at a Duluth hospital with the boy, her grandson.

Porter said she holds the baby for hours. She bathes the four-month-old and dresses him in fresh pajamas. But doctors tell her the infant can't see or hear, that his brain scans show no activity. The child will get nourishment from a feeding tube for the rest of his life; Porter said one was surgically implanted last week.

In the weeks since the baby was brought to the emergency room, there have been no arrests stemming from his injuries. Porter said the boy suffered traumatic brain injury and doctors found he had a number of broken ribs that had begun to heal.

"I want to see somebody pay for this," she said. "That little guy was perfect." He could coo and laugh, she said. Now, doctors tell her he is brain dead.

"He'll never have a life," Porter said. "It's heart-breaking."

La Lor would not confirm that this is a "shaken baby" case, but said such cases are complicated. Officers have to determine who was with the baby when the injury occurred, rule out natural factors or causes, collect medical records and often consult with outside medical experts.