“I’m devastated to be forced out of the organization I conceived to pursue rigorous, evidence-based tech accountability journalism,” Ms. Angwin said in an emailed statement. “I will continue to pursue that mission and hope to find other ways to help build this field.”

While Ms. Angwin was at ProPublica, the site became known as “big tech’s scariest watchdog.” Before joining ProPublica, she worked at The Wall Street Journal, where she led a privacy investigative team and was also part of a group that won a Pulitzer Prize for coverage of corporate scandals. She has also written two books, one of which was about privacy.

At ProPublica, Ms. Angwin’s team demonstrated how Facebook’s ad tools could be used to illegally discriminate against people of certain races, investigated racial bias in criminal sentencing software and examined how African-Americans were overcharged for car insurance. Mr. Larson was generally her partner on investigations, she said on a podcast last fall, where “he’s sort of the programmer, I’m the journalist, although I think we’re both a little of both.”

The circumstances surrounding Ms. Angwin’s departure remain a point of contention. Ms. Gardner said the site had started talking with Ms. Angwin in December about creating a new role for her that was not of editor in chief, but that would allow her to “remain the public face of the institution.” She added that Ms. Angwin was not open to other jobs at The Markup.

Mr. Larson said, “The Markup attempted to meet with Ms. Angwin in person, and discussions about her role had been ongoing for some time.” He added, “This was not abrupt.”

Ms. Angwin said she had never been offered other roles or discussed other jobs within the roughly 15-person organization.

The seven members of the editorial staff sent the management and Mr. Newmark a letter supporting Ms. Angwin on Monday, saying, “We joined on to The Markup because we believe in Julia Angwin’s work.” The letter was posted on Twitter from an account named “The Real Team Markup” on Tuesday.