ROME -- Police raided suburban traveller camps Tuesday in the hunt for the three people on the run after mugging Chinese Fine Art student, Zhang Yao, who was killed last week by a train as she pursued her assailants, police said.

 As part of the investigation to find Zhang Yao’s muggers, the Chinese student from Hohhot who was killed by a train while pursuing the thieves, police Monday fenced-in the via Salviati traveller camp nearby the Immigration Office of via Patini, where Yao had gone Dec. 5 to pick up her study permit, in the suburbs of the capital.

 During the blitz, police made the all of the travellers vacate their dwellings in an attempt to find the three muggers who were believed to have taken refuge there after stealing Yao’s bag, containing her 1,000-euro study grant.

 The police forces searched all dwellings, amongst the mountains of rubbish in the camp, and analysed all available documents. Two travellers were taken by the police, who were subsequently identified and released. A patrol of Carabinieri police also stopped two men from the camp who were in an uninsured vehicle.

 There are no signs of any attempt to reclaim or regenerate the abandoned waste-land in the zone by the government. People here live amongst enormous piles of rubbish, posing huge health risks, right under the eyes of all.

 Now that news of this tragedy has circulated the world, comment of this type are being dissipated via social media -- “I wanted to send some images of where the mugging happened and where the body was found to some Chinese friends. But I was too ashamed. There was just rubbish,” Il Messaggero writes.

 The body of the 21-year-old Chinese Fine Art student from Hohhot, daughter of a businessman from this inner-Mongolian city, was found Friday at Tor Sapienza after being declared missing by her roommate and friends.

 The arts student disappeared Dec. 5 after going to collect her study permit from the Immigration Office in the Roman suburbs, and was subsequently found dead Friday in via Sansoni, Tor Sapienza. Her body was found in a bush next to the railway line that runs next to the via Salvati traveller camp, 800 metres from the office.

 Viewing local CCTV footage, police made out three blurry figures in movement, having just stolen her bag -- one of them holding it and running, but the quality is too bad for them to be identified. Experts are working on the footage to try to improve the image quality.

 In the images, Yao then appears but she has lost sight of her muggers. She remains by herself on the train tracks, calls her father and friends and then is hit by a train which throws her into a bush, amongst rubbish. A full autopsy is being carried out Tuesday.

 The last person to have had contact with Yao was Zou Xiao, her friend with whom she shared an apartment in the Don Bosco zone. Yao had told her friend that “My bag has been stolen,” and "help I am being attacked," then there was a rustling, and a noise that sounded as if someone had grabbed her phone, then silence, Il Messaggero reported.

 Her friends are collecting signatures in a petition to have the Immigration Office moved to a different location in Rome, and local residents showed their solidarity with a sit-in Monday in the office.

 Some find it hard to believe that her death was caused by an unseen train, and many took the streets to ask Roman mayor Raggi for heightened security in the area.