The arrest follows almost three weeks of intense investigation by Tayside Police since Mary went missing in the early hours of Thursday, February 25.

Mary had been on a night out with her sister Michelle, visiting the Gauger pub in the Seagate before the pair went dancing at Fat Sam’s nightclub.

Mary left the club accompanied by a man and witness accounts and CCTV images had shown the pair walking through the city centre in the early hours of February 25.

A major police inquiry was launched after Mary failed to return home from the night out and over 50 officers were assigned to the case in the two weeks she was officially listed as a missing person.

Her body was found on an embankment off North Marketgait, close to the Ladywell Roundabout, on Wednesday of last week.

Forensic officers in protective suits immediately began searching the area, which has been cordoned off and blue sheeting erected to screen their activities, since the discovery of the body.

Officers were still at the scene today.

She was formally identified on Friday, the same day a post-mortem examination was carried out to confirm the cause of death.

Meanwhile teams of specialist officers have spent much of the past few days photographing, videoing and cataloguing the scene.

Other forensic officers were working on a footpath above the embankment which runs from Paradise Road into Dudhope Street and on to the Hilltown.

A fingertip search of the Ladywell roundabout was also conducted by police. Police also appealed to students and other revellers who were out clubbing on the night Mary and her sister went to Fat Sam’s.

Since the discovery of her body, the area has been filled with floral tributes from friends, her devastated family members, and others.

Meanwhile, tributes have flooded in to social networking sites on the Internet.