The apparent sabotage of the official investigation of the murder of Nemtsov leaves the only scientific concept about the murderer: Putin killed Nemtsov. No other person could block the traffic at the entry to the Nemtsov bridge just before the murder, block the vigilance of the bridge, block the KGBists who were spying after Nemtsov, robe the records of the Kremlin's videocameras of monitoring, and, en fin, order the investigators not to analyse the observations mentioned. The murder and the apparent sabotage of the investigation caused protests. The protesters call the place of murder Немцов мост, id est, Nemtsov bridge.
Since 2015, the memorial of Boris Nemtsov is maintained by volunteers at the place where Putin killed Nemtsov in 2015.02.27. The people bring flowers and images of Boris Nemtsov.
From time to time, the pro–Putin terrorists attack the volunteers at the Nemtsov bridge and vandalise the memorial of Nemtsov. After each of these attacks, the memorial is recovered again. 
Since the birder, Lena Hades keeps, as she calls it, the Art marathon, adding new drawings and paintings of Boris Nemtsov to the memorial. She tries to sell her works, but most of pictures she makes are just vandalised, plundered, robbed by the group of support of the killers. .
- https://www.facebook.com/photo.php?fbid=609952552472633 Sofia Nepomnyaschaya. 2015.03.30.
- https://www.facebook.com/photo.php?fbid=732918433491707 Alla Frolova. И так будет. 2015.03.26.
- http://www.vedomosti.ru/opinion/articles/2015/03/27/komu-pomeshala-tablichka-nemtsov-most Елена Мухаметшина. Кому помешала табличка "Немцов мост". Разгром стихийного мемориала на месте убийства Бориса Немцова и повестка националистов. 26.03.15. Статья опубликована в № 3799 от 27.03.2015 под заголовком: Вещь недели: «Немцов мост».
- http://www.bbc.com/news/world-europe-32053757 Nemtsov memorial on Moscow bridge vandalised. 25 March 2015.
- http://www.huffingtonpost.com/lena-hades/the-artmarathon-and-the-b_b_9329286.html Lena Hades. The Art-marathon and the Battle for Portraits on Nemtsov Bridge. 02/26/2016 04:48 pm ET.