Former city Finance Director Martha Stark agreed to pay $22,000 in fines Tuesday for violating conflict of interest rules stemming from her work for a real-estate company between 2005 and 2009.

Ms. Stark agreed to the fine, the second-largest ever administered by the Conflict of Interest Board, after investigators found she had violated city rules by using her Department of Finance email account to conduct business on behalf of Tarragon Realty Investors Inc.

Ms. Stark also acknowledged using the email account to help her domestic partner search for an apartment, and to help her stepsister look for work. She also admitted that she was "personally and directly involved" in the department's hiring of her half-brother as an aide, and that she had intervened with his supervisor "concerning supervisory and performance issues," the COIB said.

In a disposition filed with the board, she acknowledged using the city email account roughly 300 times over four years in the course of her work for Tarragon, which included sending emails to the IRS to inquire about the company's tax refund at a time when the firm was struggling with its cash levels. Ms. Stark had previously sought and received clarification from the board about how she could legally serve as a paid adviser to Tarragon while serving as finance director, but said in the settlement that she had misunderstood the board's guidance.

"I mistakenly believed at the time that it was permissible for me to use a de minimus amount of city email for my paid Tarragon Board service," she said in the disposition.