PORTLAND — The city has hired the Minneapolis-based firm of Clifton Larson Allen to conduct an investigation into the Portland Police Department’s response to a Black Lives Matter protest held June 1. A report on the firm’s findings is expected within three months.

The goal of the independent investigation “is to ensure the integrity of the department was maintained throughout its response to the protest,” the city said in a press release.

The city has allocated $40,000 for the investigation.

The June 1 protest began with hundreds of people peacefully demonstrating in the streets of Portland, but grew to 1,000 and ended with police deploying riot gear and using pepper spray to control the crowd, which police said had begun throwing bottles, bricks and rocks at officers. Close to two dozen people were arrested, mostly for failure to disperse, and many businesses were vandalized.

“It is imperative to assess not only the information presented at the time, but to seek out other relevant information that may not have come to light as yet,”  said Clifton Larson Allen Principal and Counsel Frank Rudewicz. “We look forward to providing the city and Portland community with the assessment and information necessary to move forward.”