According to a CPD community alert, in these incidents the offender meets the victim on Facebook and agrees to meet up with them in the 1200-block of South Christiana Avenue.
When the victims meet up with the offender, the person batters the victim and demands/takes property by force.
In one incident, the offender produced a knife when the victim tried to defend themselves, the community alert said.
The robberies happened on March 28 around 5:50 p.m. and April 21 around 4:19 p.m., police said.
The offender is thought to be 17-20 years old, the alert said.
Anyone with information is asked to contact Area Central detectives at 312-747-8380.