New scam against senior citizens

A man came to a house to ask if the resident was having trouble with green water. He said he was checking all the houses on the block and the resident was the last house on the block he needed to check.He was a white male ,about 6ft tall with a dark baseball cap,and normal work clothes.
He sent the resident down the basement,then proceeded to rob the resident of money and jewelry When the resident came up from the basement the person was gone DO NOT let anyone in your home without asking for ID