SAN DIEGO -- In an exclusive 10News report, investigative reporter Thom Jensen learned that the San Diego Office of the U.S. Attorney has advised the Border Patrol they want to change the way the Department of Justice does business.

In a letter written by Assistant U.S. Attorney Steven Peak to Paul Blocker, Jr., acting chief patrol agent, he said, "We believe it appropriate to revise our prosecution guidelines in criminal alien cases."

Peak said the local U.S. Attorney's Office resources are limited and they have other "enforcement priorities." He told the Border Patrol that about one-third of the U.S. Attorney's Office staff is now involved in this case and his office anticipates prosecuting about 25 percent more criminal alien cases this year.

The Department of Justice wants to "scrutinize more closely the immigration and criminal history" defendants.

As explained to 10News by Border Patrol sources, under the new guidelines, the criminal history of smugglers or illegal immigrants will be considered only if they've been convicted of murder, manslaughter, kidnapping, rape or multiple felonies in the past five years. If they have committed a crime longer than seven years ago, it will not be considered -- that includes crimes like child pornography, weapons crimes or terrorism.

Those same Border Patrol sources are furious. They said this new policy will mean releasing potentially dangerous illegal immigrants back into Mexico. And "we will be facing them the next night."

It's a short-term solution that will lead to more problems along the border in the future.

U.S. Attorney Carol Lamb defended the policy and said her office will handle these prosecutions on a case-by-case basis.

She said it's a proposal with no start date set, but agents tell 10News the changes are supposed to be implemented Monday, Nov. 1.