An Illinois teenager charged with killing two protesters days after Kenosha police shot Jacob Blake is expected to plead not guilty at an arraignment Tuesday. Local officials, meanwhile, are bracing for protests following a decision, expected in the next 10 days, on whether to charge the officer who shot Blake.

Attorneys for Kyle Rittenhouse have argued the August 25 shootings, which wounded a third protester, were acts of self-defense by a patriot who was trying to protect the city as civil unrest following Blake’s shooting left some downtown businesses in ashes. Rittenhouse, who turned 18 on Sunday, allegedly used a military-style rifle after arriving in the Wisconsin city from his home in Antioch, Illinois, about 20 miles southwest.

Wisconsin Gov. Tony Evers announced Monday afternoon he was mobilizing 500 National Guard troops before Kenosha County District Attorney Michael Graveley announces the charging decision. Evers said local authorities requested the mobilization this week.

“We are continuing to work with our local partners in the Kenosha area to ensure they have the state support they need, just as we have in the past,” Evers said in a statement. “Our members of the National Guard will be on hand to support local first responders, ensure Kenoshans are able to assemble safely, and to protect critical infrastructure as necessary.”

Kenosha officials on Sunday said they expect the charging decision “within the first two weeks of January.” In a statement the officials said their preparation includes a “demonstration space,” limits on city bus routes, “protective” fencing, road closures and a curfew.

On Monday evening, Blake’s family and dozens of supporters marched in Kenosha, demanding “justice.”

Blake, who is Black, was shot seven times in the back by white officer Rusten Sheskey as police tried to arrest him August 23. The shooting left Blake, 29, paralyzed from the waist down.

The incident, which took place about three months after George Floyd’s killing by Minneapolis police, sparked outrage and two days of chaotic street demonstrations after video of it was posted online.

Rittenhouse, a staunch law-enforcement supporter, came in response to a call for self-appointed militia members to protect businesses in that city, according to prosecutors, who say he opened fire with an AR-15-style rifle in separate downtown Kenosha locations, killing Joseph Rosenbaum, 36, and Anthony Huber, 26, and wounding Gaige Grosskreutz, 26.

Prosecutors charged Rittenhouse with first-degree intentional homicide — Wisconsin’s equivalent of first-degree murder — in connection with Huber’s death. They also charged him with first-degree reckless homicide, attempted first-degree intentional homicide, possession of a dangerous weapon by a person under 18, and two counts of first-degree reckless endangerment. Prosecutors later added a seventh charge — violating curfew the night of the shooting. All but the gun and curfew charges are felonies.

If convicted of the murder count, Rittenhouse would face a mandatory life sentence.

His lead attorney, Racine-based Mark D. Richards, did not respond on Monday to requests for comment about the arraignment.

In an October court filing, Rittenhouse’s lawyers characterized the militia members as “citizens who responded to their civic duty to help the community.”

Rittenhouse, who is white, is free on $2 million bail while awaiting trial. His case has become a rallying point among some conservatives.

Blake was discharged from a Milwaukee hospital in October and was undergoing treatment at an Illinois rehabilitation clinic, his uncle told the Associated Press.

The city of Kenosha and Kenosha County face claims totaling $20 million from Grosskreutz and the parents of Huber. The claims allege the city and county were negligent in their response to the unrest over the Blake shooting.

The Associated Press contributed reporting. Chip Mitchell reports out of WBEZ’s West Side studio about policing. Follow him at @ChipMitchell1. Contact him at cmitchell@wbez.org.