Chinese police caught over 4,200 suspects for theft of personal information in 2016, with over 1,800 cases solved, according to the Ministry of Public Security (MPS).

The police also managed to track more than 30 billion stolen personal information items last year, while nearly 100 of the suspects were hackers.

The leakage of personal information is against the country’s Civil Law, as Article 111 of the law states that the personal information of citizens shall be protected by law.

Leaking personal information has become a public nuisance in China and a crack down is necessary, said Wang Liming, a civil law expert with the China Law Society.

On a number of occasions, suspects have sent fraudulent messages to phone numbers obtained via websites that leaked the personal information of their customers.

Xu Yuyu, a high school graduate in Linyi of east China’s Shandong Province, died of cardiac arrest in August 2016 after losing 9,900 yuan (1,440 U.S. dollars) of her university tuition fees to telecom fraudsters.

The case aroused shock and anger among Chinese people, drawing attention to the protection of personal information.