April 20, 2013, was the 48th birthday of Gao Zhisheng (高智晟).
Gao is a Chinese army veteran and self-taught lawyer. He was named one of the 10 Best Lawyers in China by the Ministry of Justice in 2001. On December 22, 2006, Gao was convicted of subversion, and was sentenced to three years in prison. The sentence was suspended, and he was placed on probation for five years.
In February 2009, Chinese security agents took Gao for interrogation, and he was not seen again until March 2010. At that time he said that he had abandoned his criticism of the government in the hope of reuniting with his family.
On December 16, 2011, Xinhua reported that, one week before Gao Zhisheng's probation was to expire, a Beijing court withdrew his probation and sent him back to jail for another three years. Gao's probation had been due to expire in a week. See: http://www.china.org.cn/china/2011-12/16/content_24176428.htm
These screenshots show that on December 16, 2011, a user searching for "Gao Zhisheng" on Baidu could find around 300 results, though only from a restricted white list of about a dozen websites operated by the central government and Communist Party. By December 18, the same search returned no results, only a notice informing users "Search results may not comply with relevant laws, regulations, and policies, and have not been displayed."
These screenshots were taken on May 1, 2013, and show that most of China's major search engines and Weibo services were returning no results for searches for "Gao Zhisheng." The only exceptions were Jike and Yahoo.cn, which were restricting results to the restricted white list.