She led a successful prosecution of executives of Backpage.com, then the largest online human trafficking platform in the world,[4] that resulted in the site being shut down in 2018.

[6] The National Center for Missing and Exploited Children honored Krell with a career achievement award for her work on the Backpage case.

[9] In 2018, Krell joined Planned Parenthood Affiliates of California as their Chief Legal Counsel, seeking to help combat efforts by the Trump Administration to cut funding and curtail access to low-cost reproductive healthcare.

In that role, she filed an amicus brief defending a California law that sought to reduce targeted dissemination of misinformation about reproductive healthcare from a suit that was being heard by the Supreme Court.

[11] Krell won election to the California State Assembly in 2024 on a platform promising to prioritize public safety, protect access to reproductive healthcare, address high prices and homelessness, and improve programs benefiting vulnerable youth.