What I was told about the incident today:
Driver was a local 16 yr old boy. His parents saw the police FB post and suspected that the damaged Kia Forte in their garage was the car the police were looking for. They turned their kid in. As far as I know the kid claimed he didn't know he hit anyone, besides he was extremely upset because he had just broke up with his girlfriend.
The kid was charged with some serious crimes including leaving the scene (not sure about the others, but it doesn't sound like it's going to be swept under the rug). As the driver is a juvenile it's likely that few more details will be made public. It's impossible at this point to say whether or not he hit my brother on purpose. We may never know.
My brother was released early from the hospital today so he could visit our mom before she dies. (She's in hospice care now. The end is imminent.) He'll be finishing his physical therapy at home and will be fitted for a prosthetic soon. He is in good spirits and a full recovery is anticipated.
Thank you to everyone for their help and well wishes. I think the person who will suffer the most serious long term consequences will be the driver of the Kia.