Gregory Lee Giusti is accused of making dozens of hostile phone calls to Pelosi over health care reform.
During the hearing, Magistrate Judge Bernard Zimmerman ordered the 48-year-old to stay in the custody of U.S. Marshals pending court hearings and while the magistrate considers whether he should order a psychological evaluation.
On Monday, Giusti's public defender asked if he could be released to a halfway house while the case continues.
His mother Eleanor even made a plea, and said her son is a kind soul. She stood before the magistrate and said her son is very vocal, that he takes in all the negative of what people say in various media and uses it.
Last week in a phone interview with ABC7, she said her son got riled up by radicals on Fox News.
Prosecutors said Giusti made at least 48 phone calls and left nine voicemails threatening to, among other things, burn down Pelosi's homes in San Francisco and St. Helena if health care reform passed.
Pelosi reportedly told investigators she got a call while in Washington D.C. She said the man on the phone had said: "If health care passes, when you go back to California, you won't have a home to go back to."
In court, Zimmerman said he found that threat hard to reconcile with Eleanor Giusti's description of her son.
He added that since health care passed: "There is a danger that he will try to do what he threatened to do." He also said Giusti "does not respect authority, is not amenable to supervision" and he added "I am not prepared to accept that he is a gentle soul."
The prosecution also revealed in court that he has 15 convictions dating back to 1991 and a current bench warrant out for his arrest in Alameda County.
Some of the convictions include threats, vandalism, fraud and theft and he has also been on probation several times. The judge also noted in his order that Giusti has committed some of his crimes and been placed on probation while on probation for other cases.
Eleanor Giusti declined to talk with reporters, and his next court appearance will be on April 19.