Chennai, Dec 30 : Tamil Nadu Police in its investigation has proved that former MP and DMK's minority wing leader, Dr. Masthan was murdered. Earlier on December 22 after his passing away it was stated that the former MP died of a massive heart attack. Police initiated a probe after the son of the late leader cast doubts about his death and formally registered a complaint with the Guduvancherry police. The police on investigation found that the former MP was murdered and that it was due to a financial dispute with certain family members. Guduvancherry police later arrested Imran, Thoufeeq, Sulthan, Nasser, and Lokesh. Dr. Masthan was returning to his hometown from Chennai on December 22, after inviting several people, including Chief Minister Stalin to his son's wedding. According to reports, he complained of chest pain on his way back home and he was brought dead to a private hospital. However, now the probe by the Guduvancherry police has revealed that the former MP was murdered. Guduvancherry police did not provide further information regarding his death. /IANS