Vyacheslav Shirshov, the chief purchasing officer at AvtoVAZ

Vyacheslav Shirshov, the chief purchasing officer at AvtoVAZ, the country's biggest carmaker, was murdered Thursday in his apartment building in Tolyatti, investigators said."An unidentified assailant fatally stabbed [Shirshov] in the stomach," said Irina Doroshenko, a spokeswoman for the Samara region branch of the Prosecutor General's Office, Interfax reported.Shirshov, 37, was the director of the procurement department, which oversees contracts on raw materials for AvtoVAZ and selects suppliers.Investigators said they were considering his professional duties, mugging and score settling by his adversaries as the three primary motives, Interfax reported.Tolyatti, a city of about 700,000 people on the Volga River, was known as Russia's crime capital in the early part of the decade, when contract killings occurred almost weekly, many of them related to the auto industry.More than 500 people affiliated with AvtoVAZ have been murdered in contract killings since 1992, according to media tallies.AvtoVAZ said Friday that a criminal case had been opened and that "various versions are being looked into.'' Renault, France's second-largest automaker, agreed in December to buy 25 percent of AvtoVAZ for an estimated $1.3 billion.The deal is expected to be closed on Friday.