YAROSLAVL, February 28. /TASS/. Russia’s Investigative Committee has opened a criminal case into the murder of Yaroslavl regional legislature deputy Boris Nemtsov under articles 105 (murder) and 222 (illegal arms turnover) of the Russian Criminal Code.

According to preliminary data an unknown assailant made at least 7-8 shots at Nemtsov when the latter was walking along the Bolshoy Moskvoretsky Bridge in downtown Moscow.

An investigative group is working at the site.

The bridge has been closed for traffic.

Investigators are considering all versions when probing into the murder of opposition politician Boris Nemtsov and do not rule out it was a contract killing, senior aide of the head of the Main Investigative Department in Moscow Yulia Ivanova told TASS.

Investigators are currently questioning a woman who was with Boris Nemtsov at the moment of his murder, she told journalists.

Six bullet cartridges have been discovered at the site where Nemtsov was killed, Russian Interior Ministry spokeswoman Yelena Alexeyeva said Saturday.

"Six cartridges have been found at the site. Four bullets hit Boris Nemtsov," Alexeyeva told journalists.