FAIRFAX, Va. — Two days of testimony convinced a judge there is strong circumstantial evidence linking teenager Lee Malvo to four sniper attacks during a deadly shooting spree in October.

Juvenile Court Judge Charles Maxfield ruled Wednesday there is enough circumstantial evidence to try the 17-year-old as an adult in the Oct. 14 slaying of FBI analyst Linda Franklin. The ruling makes him eligible for the death penalty.

Maxfield's ruling came after a preliminary hearing Tuesday and Wednesday that tied Malvo to the Washington-area shootings. Prosecutors said fingerprints on the murder weapon and other evidence connect Malvo to at least four sniper attacks, three of them fatal.

The teenager also tried to extort $10 million from authorities during the attacks, prosecutors alleged.

"They wanted to negotiate for money," prosecutor Robert F. Horan said. "They said, 'If you want us to stop killing people give us the money.' If that is not intent to intimidate government, I don't know what is."

The extortion allegation is a key element of a Virginia anti-terrorism law that allows the death penalty for killers convicted of trying to intimidate the public or coerce the government. Malvo is also charged under a statute that allows a death sentence for multiple murders in a three-year period.

Malvo and John Allen Muhammad, 42, are accused of killing 13 people and wounding five others in Alabama, Georgia, Louisiana, Maryland, Virginia and Washington, D.C., last year. They are being tried first in Virginia in separate trials.

Defense lawyer Michael Arif argued the evidence presented this week was insufficient because no eyewitnesses placed Malvo at any of the crime scenes. Maxfield disagreed.

"There is no eyewitness at any of the four crime scenes but the circumstantial evidence is quite strong," the judge said.

Among the evidence was testimony from a Fairfax County police detective who identified the male voice on tape recordings of two threatening phone calls to police as Malvo's. Both tapes were played in court.

"I talked to him long enough to know he's very smooth and well-spoken. I'd know that voice immediately," Detective June Boyle testified. She described Malvo as calm, relaxed and even "jovial on occasion" during their interview last year.

Horan said after the hearing he believes money was the motive for the crime spree. He said a series of increasingly impatient phone calls and letters to police laid out non-negotiable terms for ending the sniper killings.

"Can you hear us now!" read a note left for police Oct. 22 at the scene of the final sniper shooting, which killed Montgomery county, Md., bus driver Conrad Johnson. "Do not play these childish games with us. You know our demands."

On several occasions Malvo and Muhammad taunted police, saying their "incompetence" in negotiations had cost lives, according to prosecutors.

Defense attorney Arif said the demand for money in the notes does not qualify as terrorism, and questioned whether it should be interpreted as a motive for any of the alleged crimes.

"The request for $10 million sounds like something out of an Austin Powers movie," he said.

Defense lawyers challenged whether the caller was even male. On cross-examination Boyle said she had no special training in voice identification. Maxfield said such evidence is frequently used and ruled her testimony was admissible.

Ballistics experts tied a Bushmaster semiautomatic rifle to bullets and casings found at the scenes of four of the sniper killings. And a fingerprint expert said the only identifiable prints on the rifle — found on the pistol grip — belonged to Malvo.

Prosecutors are expected to take their case against Malvo to a grand jury Tuesday, and hope to bring the case to trial this summer. After the hearing, defense lawyers said court papers, which in juvenile court are sealed, indicate Malvo's name is actually Lee Boyd Malvo.

Muhammad faces trial in October in neighboring Prince William County for the Oct. 9 slaying of Dean Meyers at a Manassas gas station.