Front Suspension Lower Ball Joint problems of the 2005 Subaru Impreza

My brother was driving his 2005 wrx sti on a clear morning on dry pavement and lost control. The car slid off the shoulder of the road and then crossed back over the road where it collided sideways with a tree. The vehicle made contact with the tree on the driver's door post, killing him instantly and injuring the passenger. Upon inspection of the car, we found that the driver's side ball joint seperated from the a-arm. It appeared that the threads on the ball joint were worn excessively and may have seperated or were seperating prior to the collision. We suspect that this could have even caused the loss of control. I know the car has an excellent safety record, but we contacted Subaru about the ball joint/a-arm. Their response was that it is not a known problem. In addition, there have been no recalls or service bulletins on this. When we sold the car for salvage, the dealer who bought it told us that he deals in wrx sti parts. He told us that this is the fifth Subaru Impreza he has purchased with the lower ball joint seperated from the a-arm. Because of the frequency of occurence, I think it warrants tracking, even if the ball joints are separating during collision. The purchaser wished to remain anonymous and again, we sold the car for salvage, but we have pictures of the car and of the a-arm and balljoint. In addition, there was no apparent damage from impact to the wheel or tire.