A physicist accused of trying to help Venezuela develop a nuclear weapon was released to a halfway house Monday after a defense attorney argued that he has posed no national security risk since his investigation by the FBI was publicized last fall.

Pedro Leonardo Mascheroni appeared before U.S. Magistrate Don Svet, who imposed several conditions on Mascheroni's release, including that contact with his sisters and nieces, who live in Argentina, is subject to government monitoring.

Svet noted Mascheroni "has the skill and science to build a bomb" and asked defense attorney Amy Sirignano why that wouldn't be considered a danger to the community.

She replied that since a search warrant was served at his Los Alamos home in October, Mascheroni has cooperated with prosecutors, surrendered his passport and rarely left the northern New Mexico town. Even when his wife went to Idaho to see their grandchildren, Mascheroni stayed behind, she said.

"If he was out there selling national security secrets, the government should not have let him stay out for the last 11 months," Sirignano said.

Mascheroni's wife, Marjorie Roxby Mascheroni, also appeared before Svet, who ordered her to house arrest.

In a 22-count indictment issued Friday, the couple were accused of offering to help develop a nuclear weapon for Venezuela through dealings with an undercover FBI agent who was posing as a representative of the Venezuelan government.

The indictment says Mascheroni told the undercover agent he could help Venezuela develop a nuclear bomb within 10 years and that Venezuela would use a secret, underground nuclear reactor to produce and enrich plutonium, and an open, aboveground reactor to produce nuclear energy.

The U.S. government is not alleging Venezuela or anyone working for it sought U.S. secrets.

The couple pleaded not guilty Monday. If convicted, they face up to life in prison.

Mascheroni, 75, was shackled at the hands and feet for his court appearance. Seated next to other defendants in orange, red and blue jail jumpsuits, Mascheroni wore a black polo shirt, white slacks and sandals.

Sirignano told Svet that Mascheroni has made no effort to flee Los Alamos over the past year. She said the former Los Alamos National Laboratory scientist spends most of his time working in his basement, continuing a 20-year effort to develop his theories of fusion.

Svet noted that the government's pretrial services had recommended Mascheroni remain in custody. Prosecutor Fred Federici said he had met with Sirignano and agreed to place Mascheroni in the halfway house, subject to conditions the judge imposed.

Mascheroni, a naturalized U.S. citizen from Argentina, can have no contact with foreigners other than his sister and nieces, cannot try to secure another passport from any country and cannot leave the halfway house except to meet with his legal team or go to court.

Svet questioned Marjorie Mascheroni's claim that she needs a public defender. The judge said a financial statement showed the couple has $3,800 in monthly income and noted the couple owns a $275,000 home and two vehicles, including a late model Lexus.

"I'm not one who believes the nature and seriousness of the offense requires citizens to finance the defense," said Svet, who ordered a detailed financial affidavit.

Marjorie Mascheroni's court-appointed lawyer, Erlinda Ocampo Johnson, told the judge the couple cannot afford to hire a private attorney.

"This case will be very costly," she said.