U.S. directs agents to cover up program used to investigate Americans

"It's just like laundering money - you work it backwards to make it clean," said Finn Selander, a DEA agent from 1991 to 2008 and now a member of a group called Law Enforcement Against Prohibition, which advocates legalizing and regulating narcotics.

The DEA program is run by a secretive unit called the Special Operations Division, or SOD. Here is how NSA efforts exposed by Snowden differ from the activities of the SOD:

Purpose of the programs

NSA: To use electronic surveillance to help the Federal Bureau of Investigation catch terrorists, the U.S. military fight wars, and the Central Intelligence Agency collect intelligence about foreign governments.

SOD: To help the DEA and other law enforcement agents launch criminal investigations of drug dealers, money launderers and other common criminals, including Americans. The unit also handles global narco-terrorism cases.

Gathering of evidence

NSA: Much of what the agency does remains classified, but Snowden's recent disclosures show that NSA not only eavesdrops on foreign communications but has also created a database of virtually every phone call made inside the United States.

SOD: The SOD forwards tips gleaned from NSA intercepts, wiretaps by foreign governments, court-approved domestic wiretaps and a database called DICE to federal agents and local law enforcement officers. The DICE database is different from the NSA phone-records database. DICE consists of about 1 billion records, and is primarily a compilation of phone log data that is legally gathered by the DEA through subpoenas or search warrants.

Disclosure to the accused

NSA: Collection of domestic data by the NSA and FBI for espionage and terrorism cases is regulated by the Foreign Intelligence Surveillance Act. If prosecutors intend to use FISA or other classified evidence in court, they issue a public notice, and a judge determines whether the defense is entitled to review the evidence. In a court filing last week, prosecutors said they will now notify defendants whenever the NSA phone-records database is used during an investigation.

SOD: A document reviewed by Reuters shows that federal drug agents are trained to "recreate" the investigative trail to conceal the SOD's involvement. Defense attorneys, former prosecutors and judges say the practice prevents defendants from even knowing about evidence that might be exculpatory. They say it circumvents court procedures for weighing whether sensitive, classified or FISA evidence must be disclosed to a defendant.

Oversight

NSA: Congressional leaders and intelligence committee members are briefed on the NSA's classified programs. The Foreign Intelligence Surveillance Court reviews and approves warrants for domestic eavesdropping.

SOD: DEA officials who oversee the unit say the information sent to law enforcement authorities was obtained through subpoena, court order and other legal means. A DEA spokesman said members of Congress "have been briefed over the years about SOD programs and successes." This includes a 2011 letter to the Senate describing the DICE database. But the spokesman said he didn't know whether lawmakers have been briefed on how tips are being used in domestic criminal cases.