Images and videos that appeared to belong to her Instagram and YouTube account contained political messages and fitness tips.
San Bruno police identified the suspected shooter as Nasim Aghdam, 39, on Tuesday night.
The woman had expressed some heavy criticism for YouTube's move to demonetize certain channels. She took issue specifically with what she believed to be a targeted reduction in viewership on her videos.
Aghdam also engaged in some political speech.
"BE AWARE! Dictatorship exists in all countries but with different tactics!," a website that appeared to be linked to Aghdam read.
Her alleged Instagram account had over 16,000 followers before it was shut down.
In one missive about YouTube's move to demonetize certain channels, Aghdam said: "There is no equal growth opportunity on YOUTUBE or any other video sharing site, your channel will grow if they want to!!!!!"
Aghdam, a resident of San Diego, reportedly drove from Southern California to San Bruno days before the shooting, the local news station KRON-4 reported.
She is believed to have used a handgun to shoot three people before fatally shooting herself.
A fourth person sustained injuries that were not gun-related.
Investigators earlier on Tuesday said they believed the shooting was connected to a domestic dispute between the woman and her boyfriend, who works at YouTube, a law-enforcement source told Business Insider. The source said authorities do not believe the woman was connected to international terrorism in any way.
San Bruno police later released a statement saying that it was still investigating a motive and that "at this time there is no evidence that the shooter knew the victims of this shooting or that individuals were specifically targeted."
Multiple local news outlets, including the San Jose-based Mercury News said that Aghdam had been reported missing days before the shooting. The newspaper reported that the woman's father, Ismail Aghdam, said she complained that YouTube "stopped everything" and told her family she was "angry."