The 30-year-old from Jilin province has worked at the station for three years. About 30 expats live in her community, and some of them like to drink, which has caused problems.

She once received a call at about 11:30 pm from a man who said several people often walked on his roof. Liu and her colleagues later discovered that three visitors from the US were walking on people's roofs at night.

"They explained that they wanted to take nighttime photos of the city, which is something they did in the US. That was the problem. Walking on the roof can bother other residents and infringe their privacy. Standing on someone else's roof is very disrespectful," Liu said.

Emotional rescue

She believes that it is important to care about the expats' mental state, too, because people can be emotionally fragile, especially when faced with problems in a strange place. Therefore, the police need to do their best to help.

She recalled a case where the driver of an unlicensed cab cheated two young Irish women of 700 yuan ($100) by giving them fake money.

The women called the police, so when Liu arrived, she calmed them down and then helped them find their hotel. Their money was returned later.

"It's not easy for people to live in a strange land. If they do not feel any warmth, they will be sad and may never return," she said.