In Goblet of Fire chapter 1, Frank lies about his wife waiting for him while he has no eye contact with Voldemort and Voldemort catches his lie. It is clearly stated that Frank and Voldemort were not facing each other.
We know that Voldemort is one of the greatest Legilimens of the wizarding world but for Legilimency you need eye contact. How did Voldemort know that Frank was lying?
"I don't know what you mean by wizard," said Frank, his voice growing steadier. "All I know is I've heard enough to interest the police tonight, I have. You've done murder and you're planning more! And I'll tell you this too," he added, on a sudden inspiration, "my wife knows I'm up here, and if I don't come back -"
"You have no wife," said the cold voice, very quietly. "Nobody knows you are here. You told nobody that you were coming. Do not lie to Lord Voldemort, Muggle, for he knows...he always knows..."
"Is that right?" said Frank roughly. "Lord, is it? Well, I don't think much of your manners, My Lord. Turn 'round and face me like a man, why don't you?"
"But I am not a man, Muggle," said the cold voice, barely audible now over the crackling of the flames. "I am much, much more than a man. However...why not? I will face you...Wormtail, come turn my chair around."