( CNN ) Anna Duritskaya , the Ukrainian model who was with opposition politician Boris Nemtsov when he was shot in Moscow , is now the focus of intense interest . A beautiful brunette more than 30 years his junior , she had been his girlfriend for 2½ years . So what is known about her ? The 23-year-old had been out for dinner with Nemtsov on Friday night . She had suggested getting a taxi , but Nemtsov did n't want to , preferring to walk , Duritskaya 's mother said . As the pair crossed a bridge in central Moscow , the 55-year-old Kremlin critic was gunned down by unknown attackers . His girlfriend was holding his hand and heard what sounded like a clapping sound , her mother , Inna Duritskaya , told CNN . Nemtsov went limp and fell to the ground , fatally shot in the back . Duritskaya is the only known witness to the shooting , which occurred 100 meters ( 330 feet ) from the Kremlin but appears not to have been captured on security cameras . Inna Duritskaya said her daughter called her right after she called police to raise the alarm . `` She was crying and she was saying Boris had been killed and he 's lying next to me , '' Inna Duritskaya said . `` She was in such shock she could n't say anything else . Just , 'Mum , Boris is killed , and he 's lying next to me . ' `` On Monday , the Russian television station Dozhd published an interview with Anna Duritskaya . She told the interviewer that she did not see who killed Nemtsov , but that when she turned around , she saw a light-colored car driving away . In an interview with CNN , Ilya Yashin , a political ally and friend of Nemtsov 's , said that Duritskaya had telephoned him immediately after the shooting and said there were several men in the car containing the shooter . Over the weekend , Russian authorities questioned Duritskaya about what she saw . While in Moscow , the model was staying at the apartment of an Nemtsov aide under constant police guard . But Moscow 's Investigative Committee insisted that she was not detained and could have left at any time . `` She said she wanted to give the testimony and took part in investigative activities understanding the importance of it for the investigation , '' a statement released Tuesday said . `` We received no complaints from Anna Duritskaya or her lawyer during her stay in Moscow . Only today , after investigative activities are over she left Russia . '' The model left the Russian capital Monday night bound for Kiev , Ukraine , said Yevhen Perebyinis , a spokesman for Ukraine 's Foreign Ministry . Inna Duritskaya told CNN that while being questioned , her daughter faced constant psychological pressure from Moscow authorities and that she fears she will be implicated in his death . In a Skype interview with Dozhd , Anna Duritskaya indicated her continued presence in Moscow after the shooting was not from choice -- and seemed to appeal to be allowed to leave . `` Now I have a status of a witness , I gave all evidence possible , I do n't understand why I 'm still on the territory of Russia . I want to go to my mother who is ill , who is in very difficult psychological condition , '' she said . `` During three days , they have been taking me together with security in police cars to the Investigation Committee and conduct the investigation . They are not explaining when they are going to release me and the reason they are keeping me here . '' Perhaps not . According to the Investigative Committee , Duritskaya signed a witness protocol and confidentiality agreement , which is standard procedure in Russia . It states that she will not share information she gave to investigators or any preliminary findings of the investigation , the committee said . `` Leaving Russia , Duritskaya expressed a wish to continue to cooperate with the investigation and to participate in any ongoing investigation if needed , '' it added . Inna Duritskaya said her daughter knew the risks of getting involved with the prominent opposition leader . `` Of course when I heard she was dating him , it was a bit of a shock , '' she said . `` Then when I met him in person , I liked him a lot as a person . He was straightforward , he treated my daughter very well , she was happy . And I could n't influence it anyway ; my daughter did what she wanted to . Of course , I was worried and scared , but I could n't change it anyway . '' Duritskaya 's reported return to Kiev means she was unable to attend her partner 's memorial service and funeral Tuesday . CNN 's Alla Eshchenko contributed to this report .
Anna Duritskaya , a 23-year-old Russian model , was Boris Nemtsov 's girlfriend . She was with Nemtsov when unknown attackers shot him dead in Moscow .