A judge has dismissed all charges of sexual assault against Vancouver Island resident Colby James Messer.

Messer was accused in the alleged sexual assault of a woman at a Denver hotel room after he and his friends attended a football game in the U.S. city last year.

The woman said in a sworn affidavit that she didn't remember getting to the hotel but remembered being sexually assaulted in the room.

On Monday, Denver District Attorney Lynn Kimbrough confirmed the remaining four charges against Messer would be dropped after "new information developed in this case that led to a determination that those charges could no longer be proven beyond a reasonable doubt."

Kimbrough added that prosecutors have an "ethical duty" to dismiss charges if there's no longer sufficient evidence to prove a case beyond a reasonable doubt.

Two of the six charges against Messer had already been thrown out following a preliminary hearing.

He pleaded not guilty at an arraignment hearing in August and was released from custody under strict conditions that included he surrender his passport and not leave the U.S.