A 16-year-old girl is the fifth person to be charged following the death of a 22-year-old man at a train station in Melbourne's outer north earlier this month.Homicide Squad detectives today charged a Pascoe Vale teenager with robbery, two counts of theft, hindering and assaulting police, and possessing a drug of dependence.She has been summonsed to appear before a children's court at a later date.The charges follow the death of Aidan Becker, an off-duty security guard who died in an alleged stabbing attack while trying to protect a 14-year-old boy at Mernda railway station on March 6.Mr Becker was located with life-threatening injuries and was treated by paramedics but died at the scene.Thousands gathered at Mernda station for a vigil to honour him a week after his death.Police have since arrested a 16-year-old, an 18-year-old and two 17-year-olds in relation to the incident, charging all four with murder and armed robbery.The 18-year is due to appear at Melbourne Magistrates' Court on June 24, with the other three to face a children's court at a later date.