The ruling means Malvo's mother, who lives in Jamaica, may not be able to appear at her son's murder trial next month.

Defense attorneys said they had planned to use video conferencing to call 20 to 30 witnesses from Washington, Louisiana, Jamaica and Antigua. The witnesses would offer testimony during both the main part of the trial and the sentencing portion, if Malvo is convicted. About seven witnesses from the Caribbean are not allowed to enter the United States.

Among those barred from the country is Malvo's mother, Una James, who was deported last year on an immigration violation.

Malvo was born and raised in Jamaica and met sniper suspect John Allen Muhammad while living in Antigua. The pair also lived in Washington state.

The defense argued that barring the video conferencing would violate Malvo's Sixth Amendment right to call witnesses on his behalf. Defense attorney Mark Petrovich said lawyers will try to find a way to bring James to the U.S. for the trial.

Prosecutors said that setting up and maintaining a video link would be too expensive and make it too difficult to cross-examine the witnesses. A defense expert testified that video conferencing would cost about $11,000.

Circuit Judge Jane Marum Roush said she did not think the video conferencing would save money as the defense contended.

Malvo, 18, is scheduled to go on trial Nov. 10 in Chesapeake in the fatal shooting of an FBI analyst. Muhammad, 42, is on trial separately in Virginia Beach. In all, the two are charged with 13 shootings, including 10 deaths, in Virginia, Maryland and Washington, D.C., last year.