A bogus police officer ordered a woman who was smoking on a Glasgow train platform to pay a £20 on-the-spot fine.
Police said they believe all three incidents are linked
The lone passenger had been smoking a cigarette at Partick station at 1110 GMT on Tuesday when the man approached.
He said he was a plain clothed police officer and gave her a fine. The victim handed over the money.
Strathclyde Police believe the same man could be linked to two similar
incidents elsewhere in the west end of the city on Tuesday afternoon.
At 1400 GMT, a 79-year-old woman and her 84-year-old husband were targeted in their home in Queen Victoria Drive.
The man said he was a CID officer and had three men in custody at Clydebank police office for fraud.
He said the men had counterfeit currency and asked the couple for a £10 note for comparison.
They refused and he left.
At 1530 GMT, he gained access to the home of an 89-year-old woman in Crow Road.
Again he said he was a plain-clothed police officer.
He was disturbed by the woman's daughter who asked for identification.
The conman said it was in his car and ran off.
Detective Constable Douglas Wotherspoon, of Strathclyde Police appealed for witnesses.