Ottawa police are asking for the public's help to identify three suspects believed to be involved in four separate armed robberies, including three incidents at grocery stores where the men tied up employees while they robbed the store.

Police say the robberies took place in a span of three months.

The first robbery happened Oct. 15, 2008 at the Bob MacQuarrie Recreation Complex on Youville Drive in Orleans.

The second and third robberies targeted a Food Basics grocery store on Merivale Road in December.

The fourth happened at an Independent grocery store on Orleans Boulevard on Jan. 8.

Police say one of the suspects has a large tattoo on his right inside forearm, which might help identify him.

The suspects are described as white males in their early 20s. The man who has a tattoo is about six-feet tall, with a medium build.

Another male suspect is described as five-foot-six-inches tall with an average build and blue eyes.

The third suspect is about six-feet tall with a medium build.

Anyone with information is asked to contact Ottawa police Det. Randy Wagner at 613-236-1222 ext.5440 or Crime Stoppers at 613-233-TIPS.