Who is it that Wormtail is supposed to murder, in GoF?

[ratalman]

No: HPFGUIDX 81528

Who is it that Wormtail is supposed to murder, in GoF?  And 
does Wormtail succeed in committing the murder he is 
supposed to commit?

On p.10, GoF, hardcover ed.,  Wormtail says to LV:  "and if we 
proceed, if I murder--"  "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 servant will have rejoined us--"

I suppose this "one more death" could be Barty Crouch Sr, but I 
don't see how the ministry could fail to notice his death.  It can't 
be Bertha Jorkins, since she is already dead by LV's hand, killed 
after she had been questioned.  It can't be Moody since Crouch 
Jr tells us he needed Moody to be kept alive to help with his 
impersonation and to provide hair for the polyjuice potion.  I don't 
see how it could be Cedric, for how could anyone have predicted 
that Harry would come to Tom Riddle Sr's graveyard 
accompanied by another tri-wizard champion?   Could it be 
Sirius Black?

Robyn