Glenview police released a surveillance photo of a man leaving the cards in the area of Central and Shermer roads. The photo was captured at about 1:45 a.m. Dec. 18.
The man is not committing any crime, but Glenview police is looking to identify the man, according to a Facebook post.
However, some residents worry that if the cards remain at the homes for days, thieves would know people are away and rob their house.
The man is described as being 30-40 years old, between 5-feet-7-inches and 5-feet-9-inches tall, about 180 to 200 pounds, long brown hair in a ponytail, short beard/goatee, wearing glasses and carrying an over the shoulder bag.
Anyone with information is asked to call the Glenview Police tip-line at 847-901-6055 or email firstname.lastname@example.org.