At the end of Goblet of Fire, after Harry returns to Hogwarts from the Little Hangleton graveyard and tells everyone that Voldemort has returned, Barty Crouch Jr. who's masquerading as Alastor Moody, acts in a rather puzzling manner.
His mission was to ensure Harry arrive in the graveyard at the time for Voldemort's rebirth ritual and he has completed it. Although Harry escaped, being a loyal Death Eater, Barty obviously knows that Voldemort would want to personally finish Harry off because Voldy's an ego-maniac, and the best way is to retain his cover and develop another plan. Instead, he takes Harry into his teacher's room, and points his wand at Harry. He mentions that Voldemort hasn't managed to conquer/kill Harry and now he'd do it himself.
'The Dark Lord didn't manage to kill you, Potter, and he so wanted to,' whispered Moody. 'Imagine how he will reward me, when he finds I have done it for him. I gave you to him – the thing he needed above all to regenerate – and then I killed you for him. I will be honoured beyond all other Death Eaters. I will be his dearest, his closest supporter ... closer than a son ...'
"Mad, am I? We'll see! We'll see who's mad, now that the Dark Lord has returned, with me at his side! He is back, Harry Potter, you did not conquer him — and now — I conquer you!"
Wouldn't Barty killing Harry would disturb Voldemort's end goal?