PHOENIX (KSAZ) - Brian Histand was a popular BMX biker and in May of 2013, he vanished on South Mountain. His car and BMX bike were located on the bottom of the mountain, but it took over three years for his remains to be discovered.
His family says they may never know what happened.
"There're more unknowns, we don't understand why 2 1/2 years ago he decided to walk away from everybody," said Michael Histand.
Brian Histand's father got the call he was waiting nearly three years for, but it didn't deliver closure. Histand's bones were found on South Mountain, his remains provide few clues as to what happened.
"They received more remains yesterday, so they have to process that as well, as of this particular moment I don't think they're going to be able to determine the cause of death," said Michael.
Investigators do not believe Brian was a victim of foul play, his family suspects he may have been disoriented, the results of taking one too many hits to the head.
"We suspect it might be related to concussions from BMX biking because he never wore helmets or any kind of head protection... we suspect that took its toll on him and created issues with his brain, and he decided to go for a long walk and never came back," said Michael.
A team of pathologists and anthropologists are currently examining Histand's remains and trying to figure out what happened.