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Free-agent NFL quarterback Colin Kaepernick posted a picture on social media this week comparing modern police officers to fugitive slave patrols.

Here's a look at the message Kaepernick posted on Twitter after the Philando Castile verdict:

The 29-year-old quarterback garnered national headlines during the 2016 season for kneeling during the national anthem, a practice later joined by other athletes across the sports spectrum. He explained the decision to Steve Wyche of NFL.com last August.

"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color," Kaepernick said. "To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder."

Those comments came less than two months after Castile was fatally shot by Minnesota police officer Jeronimo Yanez during a traffic stop last July.

On Friday, Ralph Ellis and Bill Kirkos of CNN reported Yanez was found not guilty on all the charges brought against him in the case, including second-degree manslaughter and two counts of "intentional discharge of firearm that endangers safety."

Kaepernick posted a separate message on Twitter after the verdict was announced, which read: "My heart aches for Philando's family."

Meanwhile, he's remained on the NFL free-agent market for a majority of the offseason with training camps now just over a month away.

Sheil Kapadia of ESPN.com noted Seattle Seahawks cornerback Richard Sherman is among the players who said he believes the QB is being blackballed for his public stance. NFL Commissioner Roger Goodell downplayed that belief during a Los Angeles Rams All-Access event this week.

“[Teams are] going to do whatever it takes to make their football team better," he said, per ESPN's Alden Gonzalez. "So those are football decisions. They're made all the time. I believe that if a football team feels that Colin Kaepernick, or any other player, is going to improve that team, they're going to do it."

A.J. Perez of USA Today reported Kaepernick planned to discontinue his protest of the national anthem if he's signed for the 2017 season, however.