Sampath Vidanapathirana, a councillor in the southern region of Tangalle, was tracked down and arrested in the capital Colombo last night after he failed to answer a court summons nearly two weeks ago.
"He was arrested by the CID (Criminal Investigation Department) in a house at Kotte," police spokesman Ajith Rohana said, referring to a suburb in the capital.
Vidanapathirana from the ruling People's Alliance is the main suspect in the killing of British tourist Khuram Sheikh who was shot dead on December 25, 2011, at a hotel in Tangalle.
Sheikh had been working for the International Committee of the Red Cross in the Gaza Strip.