Iowa City police have released a composite sketch of a “possible witness” to a fire that destroyed the bottom floor of an Iowa City apartment complex Jan. 29.

A Tuesday press release urged the public to call the Iowa City Area Crimestoppers for information leading to the arrest of “a person responsible for this crime,” and it offers a $1,000 reward.

The development comes after firefighters were called to a fire at 421 S. Dodge St. just before 11 p.m. on Jan. 29. All 12 residents of the six-plex were displaced following the incident, but none were injured.

Several residents and neighbors reported hearing “loud bangs” a few moments before the building caught fire, but no cause has been confirmed.

Iowa City Fire Marshal John Grier said the source of the fire remains “under investigation,” and officials have not yet determined whether the fire was arson.

“Once we know something, we’ll certainly let everyone know,” Grier said. “But we want to check everything out first.”

Iowa City Fire Battalion Chief Brian Platz said that at this point, there is no indication of whether any other causes have been ruled out.

The release said investigators are still trying to identify a witness who would have been near College Green Park or 421 S. Dodge the night of the incident between 10:30 and 11:25 p.m.

A representative from Iowa City Area Crimestoppers also told The Daily Iowan the fire at the six-plex has not been confirmed as arson, though the release referred to the incident as a crime.

“I don’t know if they’ve determined that for sure,” the official said. “But if it was something that was arson, they had someone they were looking into that may or may not have been a possible witness.”

Platz said the building has been turned back over to the occupants.

University of Iowa junior Lance Iburg said residents have not received word on when they can move back in, but owners of the building are working on scrubbing the carpets and cleaning it up.

Iburg said he has stayed in a hotel since the incident, but he plans to move in with some friends in coming days.

“We’re doing well,” Iburg said. “I’m staying with some buddies, so at least I’ll have a nice place to stay.”

The Iowa City fire officials estimated $120,000 in structural damage to the building and $15,000 in content damage following the fire.