MOSCOW, June 19 (Reuters) - A 34-year old American woman who had been missing in Russia since Tuesday has been found dead and a Russian man has been arrested on suspicion of murder, the state Investigative Committee said on Saturday. Russia"s RIA news agency said the woman, which it named as Catherine Serou, had been studying law at a university in the Nizhny Novgorod region 420 km (260 miles) east of Moscow since arriving from California three years ago. Russia"s state Investigative Committee said it had opened a criminal inquiry case into the disappearance of "a foreign citizen" and a man in his early 40s with a criminal record had been arrested over her death. It did give the names of the victim or suspect. The statement by the committee said she had left home at around 6.30 p.m. on June 15 and got into a vehicle. Her whereabouts had been unknown since then. "Today, as the result of a large-scale search operation, the body of the woman was found," it said.