Did Voldemort refer to Snape as one of the missing Death Eaters at his rebirth?

Question

In Goblet of Fire, Voldemort says of the missing six Death Eaters:

“And here we have six missing Death Eaters… three dead in my service. One, too cowardly to return… he will pay. One, who I believe has left me forever… he will be killed, of course… and one, who remains my most faithful servant, and who has already reentered my service."

The answer to How many Death Eaters died before Voldemort lost power the first time? speculates about who the three dead Death Eaters were.

We know who the last one is. I’m guessing one of the remaining two is Karkaroff. Is the other Snape? If so, which one?

Answer 1

Karkaroff is cowardly, and Snape has “left him forever”.

Snape had a Dark Mark, so he was definitely part of the Death Eater “inner circle”. He would have been expected to be there, and Voldemort calls out gaps – for example, the Lestranges – so Snape would get a mention somewhere, and this seems to be it.

In Half-Blood Prince chapter 2, Snape gets challenged by Bellatrix about his loyalty, and his apparent lateness at his rebirth:

“The Dark Lord's initial displeasure at my lateness vanished entirely, I assure you, when I explained that I remained faithful, although Dumbledore thought I was his man. Yes, the Dark Lord thought that I had left him forever, but he was wrong.”

Although Snape obviously wasn’t there to hear what Voldemort said, the wording still fits.

A lot of the chapter involves him justifying himself to Bellatrix, and explaining that his late return was to remain as a spy within Hogwarts. This includes explaining why he never sought to find Voldemort, and why he fought against him when he tried to get the philosopher’s stone.

As for Karkaroff, remember that Barty Crouch Jr. will have told Voldemort of how he testified against other Death Eaters, and has seen him growing visibly uncomfortable over the last year at Hogwarts. The description “cowardly” fits for Karkaroff, not Snape.

Answer 2

For more evidence that Karkaroff is the cowardly one, observe this dialog from Harry Potter and the Deathly Hallows chapter 33. The dialog is a flashback from a few months before the Dark Lord returns.

A whirl of colour, and now everything darkened, and Snape and Dumbledore stood a little apart in the Entrance Hall, while the last stragglers from the Yule Ball passed them on their way to bed.

‘Well?’ murmured Dumbledore.

‘Karkaroff's Mark is becoming darker too. He is panicking, he fears retribution; you know how much hep he gave the Ministry after the Dark Lord fell.’ Snape looked sideways at Dumbledore's crooked-nosed profile. ‘Karkaroff intends to flee if the Mark burns.’

‘Does he?’ said Dumbledore softly, as Fleur Delacour and Roger Davies came giggling in from the grounds. ‘And are you tempted to join him?’

‘No,’ said Snape, his black eyes on Fleur and Roger's retreating figures. ‘I am not such a coward.’

‘No,’ agreed Dumbledore. ‘You are a braver man by far than Igor Karkaroff. You know, I sometimes think we Sort too soon …’

He walked away, leaving Snape looking stricken …

Professor Snape and Professor Dumbledore both think Karkaroff is the coward one, and they're among the people who know the most about the Dark Lord, so that should be good enough proof for us.