In a minute issued by the judge in February, he said the complainant returned to India and had stopped engaging with police.
The last contact police had with the complainant was on January 27 this year which was to set up a location for an audio visual link to give evidence at a trial.
The Crown asked the judge to consider only withdrawing the charge, rather than dismissing it, which meant they could prosecute again at a later date.
"There is clearly a significant public interest in the prosecution of the crime of aggravated robbery," Judge Hollister-Jones said in the minute.
"This prosecution requires the evidence of the complainant. The most recent example of the complainant's disengagement is only two or so weeks old. It is possible that there may be a reason for the breakdown in communication," the judge's minute said.
He said under the circumstances, he would withdraw the charge rather than dismiss it.
Collier was told he was free to be released from custody because the current prosecution was at an end.