Why did Voldemort feel the need to check if Harry is still alive?

Question

When Harry 'dies' from Voldemort casting Avada Kedavra in the forest, why does he make Narcissa check if Harry is still alive?

I am not asking why Narcissa was chosen, only why anyone was chosen at all.

Before then, there is only one recorded moment when the aptly named "Killing Curse" did not do its job, and that happened to Harry.

Voldemort knows this happened because of Lily's protection of love, but there is no one there who loves Harry who would protect him and apply the love protection again.

I suspect that the reason why Voldemort checked is because he's worried that history may repeat itself (as it does), but is there any explanation that that was his reasoning?

Answer 1

When Voldemort hit Harry with the killing curse Voldemort himself was knocked down/ unconscious.

Had Voldemort, too, collapsed? It seemed like it. And both of them had fallen briefly unconscious and both of them had now returned ...

‘My Lord, let me –’

‘I do not require assistance,’ said Voldemort coldly, and though he could not see it, Harry pictured Bellatrix withdrawing a helpful hand. ‘The boy ... is he dead?’

Since Voldemort himself had collapsed and recovered, its natural for him to double check and make sure Harry didnt suffer a similar fate as he had.

There was complete silence in the clearing. Nobody approached Harry, but he felt their concentrated gaze, it seemed to press him harder into the ground, and he was terrified a finger or an eyelid might twitch.

‘You,’ said Voldemort, and there was a bang and a small shriek of pain. ‘Examine him. Tell me whether he is dead.’

The crowd of Death Eaters were also wondering if Harry had indeed died, and were nervous after seeing Voldemort collapse.

Answer 2

Harry was his enemy - and Avada Kedavra failed on Harry before.

Even when Harry was a baby (which are fairly easy to kill), and the Dark Lord had no reason to think he wouldn’t be able to kill him, he was being very cautious about wanting to make sure the boy who was foretold as the one who could destroy him was killed. He wanted to watch, to make sure Harry died, even when there was no reason to believe he wouldn’t.

“He pointed the wand very carefully into the boy’s face: he wanted to see it happen, the destruction of this one, inexplicable danger.”
_{^{- Harry Potter and the Deathly Hallows, Chapter 17 (Bathilda’s Secret)}}

The curse of course failed, and between the night he first tried to kill Harry and then when Harry seemed to be dead, the Killing Curse failed to work on Harry three times; as a baby, in the graveyard because of the twin cores, and when Harry’s wand acted against the wand borrowed from Lucius. He was cautious to see Harry’s destruction when it seemed guaranteed - after having Avada Kedavra fail on Harry three times, it’s logical he’d want to check.

Up until that point, nothing he’d tried worked - Harry survived the Killing Curse three times, as well as burned Quirrell with his touch enough to kill him, destroyed the diary, resisted possession in the Ministry, and avoided the Dark Lord’s capture despite being highly searched for. Harry had thwarted him several times by that point, so it was logical he’d want to make sure that Harry was really dead.

If you believe you’ve killed the only person who can destroy you, especially if they have a habit of surviving when they shouldn’t, it makes sense to check if they’re indeed actually dead.

Answer 3

Before then, there is only one recorded moment when the aptly named "Killing Curse" did not do its job, and that happened to Harry."

No, he also tried to use Avada Kedavra during the duel in Little Hangleton. By the time Voldemort tried to kill Harry in the forest, he had failed to kill Harry several times:

-Godric's Hollow (PS)
-Chamber with philosopher's stone (PS)
-Chamber of Secrets (CoS)
-Little Hangleton (GoF)
-Ministry of Magic (OotP)
-Battle of Seven Potters (DH)
-Godric's Hollow again (DH)

So, by one count, he had failed seven times to kill Harry, and several of these attempts involved Avada Kedavra (stopped in Godric's Hollow by Lilly's protection, in Little Hangleton by Harry's counterspell, in the Battle of Seven Potters by the golden flames).

Also, in GoF, while Crouch!Moody said that "Only one known person has ever survived" Avada Kedavra, he also said that "Avada Kedavra’s a curse that needs a powerful bit of magic behind it – you could all get your wands out now and point them at me and say the words, and I doubt I’d get so much as a nose-bleed.", which implies it can fail.

Given how many times Voldemort had failed in general, and with Avada Kedavra specifically, it was reasonable for him to exercise caution.