"He is definitely on death's door," Ann Forry said.
Michael Forry, 46, lives in Mackenzie but was in town visiting friends in Kamloops when he confronted a group of jaywalking teenagers in the parking lot outside the 7-Eleven store on Tranquille Road.
He allegedly pushed one of the teens, a 17-year-old girl, to the ground. A 15-year-old boy then allegedly hit him over the head with a longboard, which is a longer, heavier type of skateboard.
His sister says he was hit on the back of the head.
"The facts are, and I can confirm this from the hospital, that my brother was hit from behind," Forry said.
She says he suffered a serious brain injury, and is currently in a medically-induced coma.
The ordeal has been devastating for the family. Michael is a single parent to a 13-year-old daughter. He also supports his elderly parents.
Forry also says the lead investigator is not answering her phone calls.
"It's completely unacceptable. I'm so disappointed with the RCMP and so is my family," she said.
"We don't need this extra stress of having to track them down to let us know what's going on."
Police say they are investigating the incident as an aggravated assault with a weapon.
The 15-year-old initially arrested in the case has been released.
So far no charges have been laid.