A federal grand jury has indicted a Colorado man charged with threatening to kill President Barack Obama and blow up a suburban mall.

Prosecutors say that Timothy Ryan Gutierrez, 20, of the southwestern Colorado town of Cortez, e-mailed the FBI's Washington office eight days before Obama's inauguration saying: "I'm going to assassinate the new president of the United States of America. P.S., you have 48 hours to stop it from happening."

He then sent another e-mail in which he threatened to blow up the mall with 40 pounds of C4 explosive and TNT planted on seven cars parked outside, according to the indictment, which was handed up in Denver.

On Thursday, the U.S. Attorney’s Office said that Gutierrez was not yet in custody; authorities would not reeal his whereabouts, the Associated Press reported.

"Both threats were taken seriously, and both threats were investigated immediately by the FBI," said Jeff Dorschner, spokesman for acting U.S. Attorney Dave Gaouette.

Gutierrez isn’t the first person arrested on charges of threatening the new president. Suspects also have been detained in Florida, Hawaii, Mississippi and Nebraska.