Thank you for your message with attached images and for contacting Iowa State University.
Are you finding these small, reddish brown beetles in a newly-constructed apartment? I can't be certain from the pictures but my guess is that these are foreign grain beetles, a common fungus-eating insect found in damp, moldy grain, AND in new homes.
They are so common in newly-constructed dwellings that they have been nicknamed "the new house beetle." They feed on mildew and fungus that grows in the humid enclosed spaces of the wall voids after moisture was trapped in the wall during construction. They are a temporary annoyance. They cannot bite, infest the structure or live in stored food.
See the article at this website. https://hortnews.extension.iastate.edu/foreign-grain-beetle
Compare your specimens to this closeup photo. Note the small knobs at the front corners of the thorax and at the ends of the antennae. https://bugguide.net/node/view/1490788/bgimage
If my guess does not fit you will need to send samples to the Clinic for diagnosis. https://hortnews.extension.iastate.edu/pidc