Rizzo was the extra guitarist that AFI added for their last (rather uknown) album "The Boy Who Set Himself On Fire". You can tell this by looking at his hair and his t-shirt.
He didn't work out too well on tour because whenever girls in the audience giggled and smiled at him and did that little wave thing they do to say 'Oh god you're hot' he'd smile back at them. Sometimes, he'd even wink. He looked like he was REALLY enjoying himself on that stage.
Frankly, this was unacceptable. At least, according to Davey Havok who swiftly kicked him out of the band.
After he'd left, the band was interviewed by Alienated Magazine and said when asked about Richard's departure "Yeah, he smiled too much, he'd finally found some happiness when he joined the band. But it was his gross morbidness that really attracted us to him in the first place. Once we saw he was capable of positive feelings, he HAD to go. He had pretty nice hair though."