What was "one more murder" that Voldemort was planning and talking about in GoF Ch. 1?

Question

From the Goblet of Fire, Chapter 1 (THE RIDDLE HOUSE):

"If?" whispered the second voice. "If? If you follow the plan, Wormtail, the Ministry need never know that anyone else has died. You will do it quietly and without fuss; I only wish that i could do it myself, but in my present condition...Come, Wormtail, one more death and our path to Harry Potter is clear. I am not asking you to do it alone. By that time, my faithful serant will have rejoined us --"

...

"One more murder ... my faithful servant at Hogwarts...Harry Potter is as good as mine, Wormtail. It is decided. There will be no more argument. But quiet...I think I hear Nagini..."

What was that "one more murder" that Voldemort was planning and talking about? I can think of 5 possibilities (four actual and one attempted murders in GoF) but none of them fit:

• Bertha Jorkins: Was already dead, and her death discussed in that same conversation

• Frank Bryce: Doesn't seem to fit, since Voldemort didn't know he was around until after Nagini told him, several minutes later ("Nagini has interesting news, Wormtail," the vice said. "In-indeed, My Lord?" said Wormtail. "Indeed, yes," said the voice, "According to Nagini, there is an old Muggle standing right outside this room, listening to every word we say.")

• Barty Crouch Sr: Wasn't pre-planned (necesitated by him fighting off Imperius Curse placed by Jr. and escaping).

• Cedric: Wasn't planned - Harry was meant to end up in the graveyard alone.

• Harry's attempted murder: The murder spoken of here was meant to be before Harry was in Voldemort's hands.

• Also, as Xantec noted, it wasn't Moody, since he was needed alive for Crouch Jr.'s impersonation up till Harry's capture.

Answer 1

In the UK edition of Goblet of Fire, the text is slightly different:

"If?" whispered the second voice. "If? If you follow the plan, Wormtail, the Ministry need never know that anyone else has died. You will do it quietly and without fuss; I only wish that i could do it myself, but in my present condition...Come, Wormtail, one more obstacle removed and our path to Harry Potter is clear. I am not asking you to do it alone. By that time, my faithful serant will have rejoined us --"

...

"One more curse... my faithful servant at Hogwarts...Harry Potter is as good as mine, Wormtail. It is decided. There will be no more argument. But quiet...I think I hear Nagini..."

(source)

In this context, the "one more curse" that Voldemort refers to is likely the Imperius curse which Wormtail will cast on Bartemius Crouch (Sr). Which enabled Barty Jr, (the faithful servant) to impersonate Moody at Hogwarts.

(And the "obstacle removed" could be the Imperius curse which Bartemius Crouch (Sr) was using to keep Barty Jr. in line, or perhaps the obstacle referred to was (the real) Moody.)

Answer 2

I think it must refer to the capture of Moody. Wormtail would never have been able to do that alone and would have needed Barty Crouch Jnr's help. With the removal of the real Moody and his replacement with a fake the 'path to Harry Potter' was clear for Voldemort. Yes they needed to enchant Barty Crouch Snr but I think Jnr had already taken care of this otherwise how would he have been able to come and see Voldemort. All that would have been needed was for Barty Snr to have been watched to make sure he was still under control.