After reading all of the evidence, I believe we need more information, but at this time, Danny's guardian is the only likely suspect. He has Motive... The trust fund, Danny was not willing to do as he wanted, Danny was leaving him, and If I am correct, Danny also was his last link to Mark, Danny's father, whom I believe the guardian also murdered. Means... He lives in a house, the weapons are endless... Opportunity... He lived with him, any time in the night, who knows, maybe he left the party he was at, not so sure the girl friend was not part of it, he would have to get back to town some how.