Nasim Najafi Aghdam (Farsi: نسيم نجفى اقدم; also known as Vegan Nasim on YouTube,  April 4, 1979 - April 3, 2018)  was a Persian YouTuber and animal rights activist based in southern California.   She identified as a "female vegan bodybuilder [...] promoting healthy and humane living." 
According to police authorities, who received two different search warrants, she lived in her family's home in Menifee, California and at the Dove Canyon Apartments in San Diego where Aghdam lived with her grandmother. 
She spent time training to be a pilot, according to public records. 
Animal Rights Activism
As an early adult, she became an animal rights advocate.  She had a personal website dedicated to animal rights issues and veganism.  She famously protested for against the US Marines' killing of pigs in military exercise. She stated to the San Diego Union Tribune , “For me, animal rights equal human rights.” 
She had a video section on her website, as well, where she embedded videos from her YouTube channel, as well as videos from other channels that promoted her cause; most of the videos from other channels included recorded incidents of people torturing animals. There were also some inspirational videos uploaded to her 'Videos' section, including the music video of Michael Jackson's " Earth Song " and a video of Bill Clinton discussing why he went vegan. 
In addition, she posted videos of her working out. 
Nasim created her primary YouTube channel on September 19, 2010. She gained over 1.5 million views on her channel, along with over 4,500 subscribers.  In her YouTube channel's About section, she claimed to produce the first Persian TV commercial and music video; the latter was entitled "Do You Dare."  Her videos' themes centralized around animal rights and veganism. 
In January 2017, she made a video venting about her content being "discriminated and filtered." She also posted photos on her website alluding to how YouTube had demonetized many of her videos.     She also wrote a manifesto and ranted frequently about her content being censored by YouTube.  She posted the following on her website: 
There is no free speech in real world & you will be suppressed for telling the truth that is not supported by the system. Videos of targeted users are filtered & merely relegated, so that people can hardly see their videos! There is no equal growth opportunity on YouTube or any other video sharing site, your channel will grow if they want to!!!!
In another passage she wrote:
Be aware! Dictatorship exists in all countries but with different tactics! They only care for personal short term profits & do anything to reach their goals even by fooling simple-minded people, hiding the truth, manipulating science & everything, putting public mental & physical health at risk, abusing non-human animals, polluting environment, destroying family values, promoting materialism & sexual degeneration in the name of freedom,….. & turning people into programmed robots! ‘Make the lie big, Make it simple, Keep saying it, And eventually they will believe it’ Adolf Hitler,
Shooting (YouTube HQ)
She approached an outdoor patio and dining area and began to fire. Aghdam did not have an ID badge but was carrying a purse. Nobody in the facility knew who she was. They added that Aghdam got off 30 or 40 shots before turning the gun on herself. 
A possible motivation for the shooting could have been tied to her many YouTube accounts, which she says have seen a decline in viewership over the past few months.