Police are interviewing a suspect in the case of a creep who groped the same 13-year-old girl twice in two weeks aboard two different trains, police sources revealed on Thursday.

Cops say a bald creep first targeted the girl on Feb. 12 while the teen was riding in a northbound 7 train in Queens. The man – who police said was 5 feet 8 to 5 feet 10 and about 200 pounds — touched the teen’s upper inner thigh as the train pulled into Queensboro Plaza.

Two weeks later, the same thing happened – this time on the 5 line as the train pulled into the 149th Street/Grand Concourse in the Bronx.

Cops nabbed the suspect on Thursday but they have not yet charged him, sources say.