In both cases, offenders approached victims at sidewalk ATMs and demanded valuables.
Investigators have connected two specific cases: One in the 3400 block of N. Clark around 1:30AM on Saturday, January 16; and the other in the 3500 block of N. Clark at 3:30AM last Wednesday.
The offender in the first incident is described as a black man, 25- to 35-years-old, 6-feet tall, and 190 pounds.
Three offenders were involved in the second robbery. The trio surrounded the victim at the ATM, police said in their alert. All three were described as black men with two being between 20- and 25-years-old.