A federal grand jury is investigating the death of an illegal immigrant from Mexico who was shot by U.S. border authorities with a stun gun, suggesting the government is considering criminal charges after more than two years of silence on the politically charged case.

Eugene Iredale, an attorney representing the family of victim Anastasio Hernandez, told The Associated Press on Wednesday that he understood attorneys from the U.S. Justice Department's civil rights division have been presenting evidence to the grand jury.

A person other than Iredale who is close to the Hernandez family said two eyewitnesses to the incident have been called to testify Thursday in San Diego. The person, who spoke directly with the witnesses, requested anonymity because grand jury proceedings are supposed to be secret.

One expected witness is Humberto Navarrete, whose grainy cellphone video at the San Ysidro port of entry captured audio of a man believed to be Hernandez pleading for help and passersby asking that he be left alone, one person said. The other was a companion of Navarrete that night.