MIAMI (AP) -

Mexican authorities are expected to release a Marine veteran jailed there for carrying across the border a shotgun with a barrel that's an inch too short.

 A press release from Florida's U.S. Senator Bill Nelson said a Mexican embassy aide told his office that Jon Hammar would be released Friday.  A U.S. Consulate official said they're standing by to escort the 27-year-old safely back to the U.S.

 His family said Hammar has been held in Matamoros since August on charges that he tried to enter the country with an illegal weapon. Mexican law bans shotguns with barrels of less than 25 inches. The family said his shotgun has a barrel of 24 inches.

 Hammar's family said he was being held in isolation after they received threats to his safety.