(CNN) -- A man who allegedly threatened to decapitate Rep. Tulsi Gabbard of Hawaii appeared in court Friday in San Diego and was ordered to remain in jail for now.
Aniruddha Sherbow made two threats to murder the Democratic congresswoman earlier this month, according to newly unsealed court documents.
On August 1 the man allegedly left an expletive-laden voicemail on Gabbard's cell phone, with the message including a threat to her life. An affidavit said that Gabbard had been getting harassing messages from Sherbow since 2011 and identified his voice as the caller. The court document said Sherbow's mother later listened to the recording and told investigators it sounded like her son.
On August 3 Sherbow allegedly sent an e-mail to the FBI and some unnamed media outlets and identified himself by name, according to the affidavit. The subject of the e-mail was "Cutting Off Tulsi Gabbard's Head."
The message said in part, "I, Aniruddha Sherbow, with the Divine as my witness, do hereby solemnly vow to find Tulsi Gabbard, wheresover she may be, and to sever her head from her body."
According to the court affidavit, Sherbow's father said he received a copy of that e-mail and he identified his son as the sender.
The FBI and the U.S. Capitol Police said Thursday that Sherbow's threats were "deemed credible."
Sherbow, 43, was arrested by Mexican law enforcement officers in Tijuana on Wednesday. The former resident of Hawaii was then turned over to the FBI in San Diego. He faces a charge of transmission of threats in interstate commerce.
He is scheduled to have another court hearing on September 12, and officials eventually want him transferred to the District of Columbia for trial.
Gabbard's office would not comment on Sherbow's arrest and the allegations against him. Press secretary Heather Fluit would only say the congresswoman was "grateful for the work" of all the law enforcement officers involved in the investigation.
CNN's Laurie Ure contributed to this report.