Three videos leaked to YouTube this month, showing alternative endings to last week's Shortland Street finale, were loaded on the TVNZ website three days before the alleged leak.
Regan Cunliffe, the creator of Shortland Street fansite Street Talk, watched the videos on the TVNZ website before they featured on YouTube and is adamant the leak was a publicity stunt.
Mr Cunliffe said material is regularly loaded on to the TVNZ website in advance of programmes screening.
Though the pages are not directly linked to from the main menu, they can easily be uncovered by accessing the website's image and video directories.
It is the same method 14-year-old Kyle Wadsworth used to access a trial version of TVNZ's on-demand service this year, Mr Cunliffe said.
The Taranaki schoolboy embarrassed the broadcaster by posting details from the supposedly secret site.
"We've told TVNZ about this numerous times. We've told them how to fix it and provided instructions," Mr Cunliffe said.
"This seems awfully coincidental after all our discussions and the big hype around the season finale.
"They know that the hardcore fans are constantly loading that directory to see if there's anything new put in there."
The situation could easily have been avoided by disabling public access to the directories, Mr Cunliffe said.
Nurse Joey Henderson (played by Johnny Barker) was unveiled as the Ferndale Strangler on Friday night, much to the surprise of viewers.
None of the three leaked videos had featured Henderson as the killer.
TVNZ did not return calls for comment yesterday. Earlier, Shortland Street producer Jason Daniel said the four endings were all filmed around the same time, in late October, and the leak had not affected which ending screened.
"That was always intended as the ending ... after we filmed those endings, we also have to film what follows after them. We can't film alternative versions of all the storylines. There can only be one ending."
Mr Daniel said the producers did not reveal the existence of a fourth ending when the leak was first reported as it would have ruined the surprise for viewers. "[It] would have eliminated the suspects featured in those endings and spoiled the fun for viewers eagerly anticipating our finale."
Friday's cliffhanger saw close to 625,000 people tune in.