Embattled Multnomah County Chairman Jeff Cogen suffered a major loss today: His chief of staff, Marissa Madrigal, resigned to take a job in the county's human resources department.

Cogen, the county's top elected official, is currently under criminal investigation by the Oregon Department of Justice, which is examining the circumstances around his nearly two-year affair with county employee Sonia Manhas.

Madrigal ran Cogen's first campaign for county commissioner and became his chief of staff in 2006.

As Cogen's chief of staff, Madrigal, 35, acts as the gatekeeper for her boss, and was key to helping him craft policies and the county budget. She also directly supervises his staff and the directors of communications and sustainability and works closely with the county's chief operating officer, Joann Fuller.

But emails between Cogen and Manhas, director of the county health department's office of policy and planning, showed Manhas was eager to go around Madrigal to communicate directly with Cogen about health department priorities.

Normally, such communication would have flowed through Madrigal or Manhas' boss, health department director Lillian Shirley. 

Madrigal's decision to leave Cogen's office leaves him even more isolated because county officials say she has been conducting much of his office's business while Cogen waits for the results of the DOJ investigation.

Her move also comes at some personal sacrifice: Madrigal will take a pay cut from $105,000 to $99,000. She is replacing a recently retired HR strategic project manager working to retool the county's personnel management.

Madrigal declined to comment on Cogen, citing her long and positive tenure on his staff.

"I love the county," Madrigal says. "This is a great opportunity to do some different work and contibute in a different way. I would sweep the floors here if necessary because the county's work is so important. I had a child at a young age. I've been poor, my family has struggled and I understand what people are going through who need our services."

Madrigal's resignation also creates an odd power vacuum atop the county, since she is Cogen's designated successor should he step down. (Unlike other elected officials, county commissioners name the person who would take their places in the event of an untimely exit.)

She expects to start her new job by the first of October. 

UPDATE, 4:27 pm: Through a spokesman, Cogen issued the following statement:

"I am very happy for Marissa and the county that she has this opportunity," Cogen said. "She has been a great chief of staff who has a lot of knowledge about how the county operates. This is a chance for her to branch off and try something new. I wish her only the best."