Authorities believe they have captured a trio of robbers responsible for more than three dozen holdups that terrorized Asian restaurants and check-cashing businesses across the Lowcountry over a two-year span.

A federal grand jury indicted 29-year-old twin brothers Raynard and Winard Eady of North Charleston and 33-year-old Christopher Donnell Simmons of Wadmalaw Island in connection with a string of 39 armed robberies that stretched from Walterboro to Holly Hill.

They are charged with conspiracy to commit robbery and using handguns in those robberies, according to U.S. Attorney Bill Nettles.

The conspiracy charge carries a maximum sentence of 20 years in prison, and the firearm charge carries a mandatory five years in prison for a first offense and a mandatory, consecutive 25 years for any subsequent offense.

Nettles said the robbers primarily preyed on businesses in Charleston County, but ventured into Walterboro, Holly Hill and Georgetown as well between July 2009 and March 2011.

The robbers first feasted on Asian restaurants, then changed up their tactics to target check-cashing and loan businesses, said Assistant U.S. Attorney Nathan Williams.

The string of Asian restaurant robberies was so prolific that authorities formed a law enforcement task force to tackle the crime wave. They also offered a $20,000 reward.

Fear in that restaurant community was palpable at the time, as some places were hit more than once. Several workers told frightening stories about having guns waved in their faces while frightened family members looked on.

The task force eventually arrested Raynard Eady and Simmons in February 2011 on suspicion of robbing finance stores. Authorities called them “persons of interest” in other robberies at the time, without drawing a direct connection to the Chinese restaurant holdups.

Authorities arrested Simmons on armed robbery and kidnapping charges in connection with a heist at a Cash Advance store in Georgetown. Arrest warrants said Simmons forced a store employee at gunpoint to the front of the store and shut her in a bathroom.

Investigators arrested Raynard Eady on an armed robbery charge in connection with a holdup at U.S. Money Shops in Moncks Corner. The warrant in that case said Eady held two victims at gunpoint while taking about $2,000.

Both men remained in custody since their arrests last year, and authorities arrested Winard Eady on Friday.

All three men appeared in jail jumpsuits Tuesday at arraignment hearings in federal court, where a magistrate judge read an indictment connecting one or more of them to robberies at a Cash Advance store in Georgetown and three Chinese restaurants — Ocean Dragon in Holly Hill, China Wok in Walterboro and China Taste on Johns Island.

Investigators with the FBI, the State Law Enforcement Division and 15 local police departments and sheriff’s offices worked together on the case that led to the recent indictments. The court filings remained under seal late Tuesday.

Simmons was detained after he waived a bond hearing Tuesday, and the Eady brothers have bond hearings this week.

Reach Allyson Bird at 937-5594 or Twitter.com/ allysonjbird.