Pacteau was given a 23-year jail sentence after pleading guilty to battering Karen to death with a hammer before trying to dispose of her body in chemical liquid.
In 2013 he avoided prison after being found not guilty by a jury of trying force a 24-year-old woman to perform a sex act on him.
The alleged incident took place in Baliol Lane, off Glasgow’s Woodlands Road, in November 2011.
Detective chief inspector Allan Burton now believes the case could return to court.
Speaking on Disclosure: The Murder of Karen Buckley, an Irish TV documentary, Burton said:
“He was found not guilty by a jury, but there’s still an opportunity that it might end up back in court.
“We spoke to witnesses involved in the case but there may be others that did not come forward. If you are one of those people, I would love to hear from you.”