Hush-Hush, High-Tech Tracker Plays Key Role in Bank Robbery Trial : Crime: Law enforcement officials try to conceal workings of electronic device that assertedly led police to defendant.

A federal trial began Tuesday for a man accused of bank robbery who was nabbed with help from a new high-tech tracking device--an instrument whose workings law enforcement officials are trying to keep secret and prosecutors have asked not be revealed in open court.

Since its introduction in Orange County in fall of 1989, the electronic tracking system has been used to catch at least six people suspected of bank robbery and other felony suspects.

However, Joseph Dion McLeod, a convicted felon charged with robbing banks in San Bernardino and Garden Grove, is the first person assertedly tracked in Southern California to come to trial, said H. Dean Steward, who heads the federal public defender’s office in Santa Ana and is defending McLeod.

Steward has argued that the device, essentially a silent tiny “beeper” that is planted in the loot and emits a signal that police can track, is “inherently unreliable.” In court documents, he also argued that its use is an unconstitutional invasion of privacy, since police can track it only to a general area and not to a specific getaway car.

The manufacturer, Electronic Tracking Systems Inc. of Plano, Tex., has consistently refused to comment on the transmitter, and both the company and the FBI have asked newspapers not to publish details about how it works or where it is used. However, law enforcement officials have called it highly effective, and a Florida security expert interviewed by The Times described it as having “90% reliability.”

McLeod is charged with stealing more than $3,900 from Pacific First Bank in San Bernardino in an armed holdup Aug. 23, and netting $660 in an armed robbery of the Bank of America branch on Chapman Avenue in Garden Grove on Sept. 21.

At the Bank of America branch, the tracking device was included in a stack of $1 bills that a teller handed to the robber, Assistant U.S. Atty. Jody Tabner Thayer told the jury Tuesday. The signal, which can be picked up within a 2- to 3-mile radius, alerted a patrolling Garden Grove police officer, who ultimately arrested McLeod and an accomplice in a red pickup truck with the money and the beeper, Thayer said.

“If a police officer is in a car and if his tracking device is activated, he knows he’s within 2 to 3 miles of an activated money pack,” she said.

That, however, is all the jurors will be told about the device.

In a pretrial hearing last month, Steward asked U.S. District Judge Alicemarie H. Stotler to exclude evidence police obtained by searching the pickup, arguing that because the beeper is unreliable, police did not have probable cause to search the truck and the search was therefore illegal.

Prosecutors argued that the beeper signal gave the police officer sufficient basis to stop the pickup truck. Furthermore, after Garden Grove Police Officer Karl W. Mansfield tracked the signal to a group of six to 10 vehicles, he heard a radio report that the suspect vehicle was a red Toyota pickup--and one of the cars in the group was, in fact, a red Toyota pickup, the prosecution said. The tracking device also helped the officer find the money, they said.

Thus, prosecutors argued, the search was legal. The judge agreed and allowed the evidence to be presented to the jury.

On Tuesday, before the jury was selected, Thayer, joined by an FBI agent, asked the judge not to allow Steward to cross-examine the police officer about the details of the tracking device.

“I don’t plan to go into how the transmitter works” or how commonly it is used, Thayer told the judge. “The law enforcement people have concerns about too much information about the system . . . ‘getting out,’ ” she said.

In addition, Thayer said, a police officer would not be qualified to discuss the technical workings of the device.

Judge Stotler granted Thayer’s request in part, agreeing that “no secret or proprietary technical information” should be disclosed and noting that the officer was not qualified to answer technical questions about the device.

Steward told the judge, “I do continue to be amazed at the FBI and local law enforcement’s fright at having anything disclosed.”

Outside the courtroom, Steward said that as judges agree to admit the device as evidence, the FBI’s insistence on secrecy makes it difficult for the defense to challenge the reliability of the device “the way I’d like to.”

In McLeod’s case, however, the prosecution has assembled much other evidence against him. On Tuesday, Thayer called two Pacific First Bank tellers to the stand. Each identified McLeod as the robber who pointed a gun at a teller and threatened to shoot.

In opening arguments, Thayer told jurors they would also hear eyewitness identifications from other tellers, as well evidence from a police officer who searched McLeod’s hotel room and found a torn section of the Yellow Pages with listings for banks, a small notebook with the addresses of banks handwritten in, and a BB gun, which prosecutors allege was used in one holdup.

In the closet of the hotel room, in the pocket of a man’s suit coat, police also allegedly found a fake mustache kit.

In his opening arguments, Steward told the jury that McLeod was not the robber, that surveillance photographs and the method of the robbery would show that different people had robbed the two banks, that witnesses had given widely varying descriptions and that the photos did not look like McLeod.