Updated: Nov. 17, 10:57 a.m.

Activists are asking why Dr. Martens chose an image that resembles a classic white supremacist skinhead symbol for a holiday billboard in inner Southeast Portland.

The billboard, which is visible at Southeast Madison and Seventh Avenue, displays black boots with red plaid laces and the phrase, "Rock the holidays." On Twitter, anti-hate group activist Sam Sachs pointed out that black Dr. Martens -- colloquially called "Doc Martens" -- with red laces are a white supremacist symbol that implies the wearer has committed an act of violence.

The Southern Poverty Law Center lists Dr. Martens with red or white laces in the "Racist Skinhead Glossary."

According to Randy Blazak, chair of Oregon's Coalition Against Hate Crime and a criminologist who specializes in hate groups, Dr. Martens have been connected to racist skinheads since the 1970s.

Black Dr. Martens with white shoelaces are a symbol of "general white power," Blazak said over the phone Thursday.

"The idea," he continued, "is that you graduate from white laces to red laces once you've spilled somebody's blood."

Blazak said he knows Dr. Martens has been working to distance itself from the racist skinhead image and he is surprised it would allow an ad like this to be displayed, especially in Portland.

"In Portland, where we're tagged as 'Skinhead City,'" he said, "it's triggering."

It's been 29 years since Mulugeta Seraw was murdered in Portland by three racist skinheads, he pointed out.

"If I was an Ethiopian person or a person of color," Blazak said, "I would say, 'that's racist Portland right there.'"

The symbol has known to activists in Portland. It drew an angry response outside of Jeremy Christian's first hearing when a man who said he was Christian's friend stopped to lace up his red laces with black boots.

The crowd called him a "Nazi" and "Facist Neo-Nazi" but the man said, "I'm not going to get into a debate with people. I know I'm a good person."

Christian is accused of stabbing three men, leaving two of them dead and one wounded, on the MAX train in May during what witnesses said was a racist rant against two teenage black girls, one who was wearing a hijab.

Several messages left at Dr. Martens corporate office in Portland went unreturned Thursday and Friday.

Margaret Haberman contributed to this report.

-- Lizzy Acker

503-221-8052

lacker@oregonian.com, @lizzzyacker