The last remaining suspect charged with being a member of a band of heavily armed robbers that struck six Washington area banks was arrested yesterday in a Texas border town, authorities said.

Omar Holmes was captured about 4:50 p.m. EST outside an Office Depot as he was about to get into a car. He was being held at the FBI office in Laredo, Tex., said Debbie Weierman, an FBI spokeswoman in the District. Federal law enforcement officials said Holmes might have been planning to slip into Mexico.

U.S. marshals had been tracking Holmes for several days as he traveled across the country with his father, Ronnie, said Deputy U.S. Marshal Sean McLeod of the Capital Area Regional Fugitive Task Force.

The men had been driving in Ronnie Holmes's Toyota Camry, authorities said.

McLeod said authorities were investigating whether Holmes's father was helping his son escape a federal indictment, unsealed last week, charging him with conspiring to commit bank robbery and armed bank robbery.

Both men were being held at a local jail last night, McLeod said.

Omar Holmes, 26, of the 900 block of Euclid Street NW, is one of nine men charged with being members of a gang of bank robbers who stole about $361,000 in six holdups in the District and Prince George's County. The other suspects have been in custody since at least last week.

Authorities said others might be charged in connection with the robberies.

One suspect has already pleaded guilty and is cooperating with investigators, authorities have said.

Federal law enforcement officials and local police have said robbery gang members methodically planned each robbery. They obtained masks, body armor and a cache of assault weapons and did not hesitate to use the guns to intimidate employees and patrons, officials said.

"They operated that robbery ring with an impressive level of planning, preparation and operational discipline," U.S. Attorney Kenneth L. Wainstein said last week.

The robbers burned some of their getaway vehicles after the heists, and some members of the gang are accused of firing shots during some of the holdups.

One member was accused of shooting at a Prince George's police officer.

The robberies started in January and continued through June, when a television cameraman on another assignment filmed the getaway from a bank robbery in Northwest Washington.

The robbers' heavy firepower concerned law enforcement officials, who feared a bloody gunfight between police and the gunmen.

Staff writer Allan Lengel contributed to this report.