CHICAGO (CBS) -- While flames coming out of a backyard grill unusual, what's burning is.

CBS 2's Steven Graves reports the post office inspector general is investigating. That's because the items in that grill are believed to be mail. And the person trusted to deliver it is suspected of the crime.

It is the type of backyard barbeque that would make a lot of people hot with anger. Flames still shooting from the debris inside when Chicago police responded around 10:00 Tuesday night.

Video shows detectives collecting evidence and taking pictures of the smoldering smoke pile of paper. A man was arrested after the incident at a home near 84th and South Crandon in South Chicago. A woman who answered the door Wednesday would not say if he lived there.

Chicago police said officers initially took the man into their custody. Soon afterwards officials released him to U.S. Postal Inspector General Agents. The United States Postal Service confirmed it's investigating the mail burning.

A careless and perhaps infuriating act of disposing mail isn't new. CBS 2 reported in 2019  who residents believe was a USPS mail carrier in Wrigleyville seen dumping current bills and credit card statements. Residents found them with the bucket in a dumpster.

In the same year, at another location in North Lawndale, a trash pickup worker found loads of mail. And residents seem to be fed up. The recent burning incident comes on top of mail frustrations in the area.

People complained Wednesday of lost mail at the nearest post office at 93rd and South Chicago Avenue. A supervisor there said she was not aware of the crime.

All the U.S. Postal Service will say is that it is investigating. No word of charges yet in this federal offense.