Strange boy at Riddle Manor

[burnoweatherhead]

No: HPFGUIDX 101084

Excuse me for not having GoF to hand for precise quotes - I've loaned 
it out - but I'm confused about Riddle/Voldemort's chronology and 
family history. In particular, who are the three Riddle family 
members that Frank Bryce is suspected of killing at the start of 
GoF? - the maid finds the parents and their "grown-up son" dead, and 
Frank is suspected but never charged. His only statement is that at 
the time of their deaths he saw a strange pale teenager with dark 
hair.

So who are these 3 Riddles in Voldemort's chronology (since I thought 
he was abandoned by his father, and his witch mother died and left 
him to be brought up an orphan)?

Also, who was the teenager Frank saw? Was it Tom Riddle? Or Harry 
using a time-turner from Books 6/7? I don't believe this has been 
explained, but apologies if it has.

Burno