The Boston Police Department’s Internal Affairs unit is investigating allegations that a Boston police officer posted offensive images online, a department spokesman told WGBH News.

Boston Police spokesman Sergeant John Boyle said BPD received a complaint about several social media posts on Wednesday and immediately took the complaint to the Internal Affairs Division, which is now conducting its investigation.

Boyle called the posts “disturbing” and said that the investigation “is being taken very seriously.” He said late Friday the officer linked to the social media posts — Carlson Breneus — had been transferred from the specialized Drug Control Unit to a different post.

Breneus did not respond to attempts by WGBH News to reach him for comment.

The investigation relates to several tweets by a Twitter user named Frederick Joseph, that he said were screenshots of images posted on Instagram by Breneus. The images seemingly mocked a disheveled older man.

Joseph, who lives in New York, told WGBH News that the Instagram posts were brought to his attention by a friend in Boston who knows the man depicted in the images.

BPD’s Boyle said he could not confirm whether the images were originally posted by anyone in the Boston Police Department.

Boyle also could not say how long the internal investigation might take.

The images consist of several photographs, some clearly photoshopped, of the same man’s face.

In one clearly digitally altered image, the man is depicted holding a rifle pointed at the head of another man.

Joseph said he captured the images from an Instagram account under Breneus’ name, and the account has since been shut down. WGBH was unable to locate an Instagram account for Breneus.