Investigation commissioners (lianfangshi 廉訪使, full title suzheng lianfangshi 肅政廉訪使), heads of investigation commissions (lianfangsi 廉訪司), were officials communicating between the local administration and the central government. The office originated in mounted couriers (zouma chengshou 走馬承受) and was in use during the Southern Song 南宋 (1127-1279) and Yuan 元 (1279-1368) periods. It belonged to the regional organisation of the Censorate (yushitai 御史臺), and was thus entrusted with the supervision of the performance of the local officialdom (see zhengji 政績). Under the Mongols, they reported to central Censorate in Dadu 大都 (today's Beijing) and the Branch Censorates (xing yushitai 行御史臺) of Jiangnan 江南 and Shaanxi 陜西.
In 1269, Qubilai Qaɣan (r. 1260-1294) created commissions in charge of judicial matters and investigations (tixing anchasi 提刑按察司), first just for four circuits, but then empire-wide, with 22 circuits in 1281. The term suzheng lianfang shi was introduced in 1291. After the demise of the Yuan empire, the office was in 1367 renamed tixing anchashi 提刑按察使.
The commissioners had official rank 3A and were entrusted with the inspection of local officials below rank 6. Their inspection tours began in the 8th lunar month and ended in the 4th month of the following year. Apart from administrative performance, the investigation commissioners had judicial rights and judged minor offences of the officialdom and complicated cases involving commoners. They were the forerunners of the surveillance commissioners (anchashi 按察使) of late imperial times.