It's one of the oldest scams around, but it's still thriving - at least in the Mount Greenwood and Morgan Park neighborhoods.

Chicago police are investigating a pattern of scams in which senior citizens are being targeted. The offenders approach seniors' houses and use a ruse to enter the homes by claiming that they are employees of a utility or service company.

They tell the victims that they are there to test the house, and once they are inside, they remove small items and cash.

The latest string of events was first reported was Feb. 6, and the latest was reported March 21 in the 3400 block of West 115th Place. According to police, when an elderly woman answered her front door, a man pushed his way past her and opened the rear door to allow another man in. The woman screamed, and the men fled.

Police say such intruders typically make out with small amounts of cash and jewelry and that the victims don't always realize that they have been robbed until long after the men leave.

The incidents usually occur between noon and 5 p.m. Police are urging neighbors in the area to watch for suspicious activity, especially near the homes of seniors.