She added: “In between the station and the hotel he had thrown Rhiannon’s phone into a river.
“Once at the hotel he was seen dancing and laughing, clearly excited about what he had done.”
The train she had been due to catch pulled in at 23:24 and the driver saw a figure slumped on the platform, the court was told.
Ms Heeley said the guard tried to help her, along with another employee from the hotel, but nothing could be done to save her and she died on 23 October, having never regained consciousness.
The court was told 11 of the 23 stab wounds penetrated her skull, one of which damaged the brain stem, causing her death.
She also had injuries to her chest and arm, indicating she had tried to defend herself, the court heard.
The puncture wounds had the appearance of a cross-headed screwdriver, which has never been found.
Ms Heeley said: “He left her bleeding to death and then casually went back to his hotel. We say you can be sure he is guilty of murder.”
The trial is expected to last about three weeks.