BOSTON (AP) _ It didn't take Boston police long to track down three suspects in an armed convenience store robbery.

Authorities say the men were all wearing court-ordered GPS devices for unrelated cases, which placed them inside the Dorchester store and allowed investigators to track them to an apartment a block away.

Police say the suspects entered the store at 6 p.m. Wednesday. All three wore masks and one had a gun.

They made off with cash and cigarettes.

All three pleaded not guilty at their arraignment Thursday. Two had their bail revoked in prior cases. A third was held on $50,000 bail.

The prosecutor said ``all their GPSs pinged to the store at the time of the robbery.'' Police also found evidence in the apartment that tied them to the robbery.

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