PEDRO has traveled more than 1,800 miles by bus and foot from his native Oaxaca in southern Mexico on his way to a promised job in landscaping in Los Angeles. The first thing he wants to know as he peers through a hole in the solid-steel fence that separates him in Tijuana from what he perceives will be ''prosperity'' in the United States is, ''Do they really have an ojo magico?''
''They'' are the United States Border Patrol, and the ojo magico (magic eye) is an infrared night-vision camera that picks up any heat-producing object, like a human being, passing within the telescopic camera's 360-degree scan.
And yes, indeed, Pedro, they do have one.
A quarter-mile away from Pedro on a flattened hill in no man's land on the San Diego side of the border, Border Patrol agent Jay Stiles is just settling into the driver's seat of a Ford Bronco that will be his post for the night. The telescope of the $250,000 ojo magico protrudes from a hole cut in the rear roof of the vehicle.
''We pick up [on the camera's monitoring screen] all the rabbits and dogs in the area, but we also get the aliens,'' says Marco Ramirez, an 11-year veteran with the Border Patrol, who is in another vehicle, looking for border-crossers.
When agent Stiles picks up ''traffic'' in the border zone, he radios the location and direction of travel to nearby agents, like Mr. Ramirez, so they can move in for an arrest. ''Night used to be our downfall,'' Ramirez says, eyeing the telescope. ''But we're doing better with this baby.''
The ojo magico is just one example of how the battle against illegal immigration is shifting from a traditional strategy of a cop on the beat - or ''cowboy,'' as agents were often known - to a more high-tech, integrated operation.
Besides daytime and night-vision cameras, the Border Patrol has installed in heavily traveled sectors ground sensors that signal any foot traffic to radio dispatchers miles away - who in turn radio patrolling agents about the activity. High-intensity lights now turn the night into day in some border regions.
Some sectors have helicopters, and fleets of shiny four-wheel-drive vehicles flank any Border Patrol office on the Mexican border.
Beyond that, however, the Border Patrol has added new computer systems to identify and catalog every apprehended illegal alien, with the idea of tracking repeat border- crossers and pinpointing criminal aliens - drug smugglers, street criminals, and ''coyotes'' or immigrant smugglers - for deportation or even prison.
Farther upstream, the Immigration and Naturalization Service (INS) last year tried out in southern California a pilot employee-eligibility program that allows companies to quickly determine by computer a job applicant's status.
In all, the INS earmarked nearly $158 million of its 1995 budget increase for acquisition and development of technology.
And more is on the way.
''We are developing a coordinated effort in which our enhanced manpower teams up with more and better technology to achieve our goals of stopping illegal immigration, facilitating legal border transactions, and getting the criminal aliens off our streets,'' says Alan Bersin, US Attorney General Janet Reno's special representative for Southwest border issues.
The strategy is in part a response to the more sophisticated methods that would-be immigrants and those smuggling them have developed over recent years. False documents that easily pass at a cursory glance are now sold by rings in Mexican border cities. An alien-smuggling operation that worked through South and Central America brought mostly Indians and Chinese into the US - at $6,000 a head.
The effort described by Mr. Bersin, US attorney for the Southern District of California, is also designed to curb illegal immigration so as to defuse it as a political issue, one that is fomenting anti-immigration proposals the Clinton administration does not favor.
Bersin opposes measures like California's Proposition 187, which sought to cut off alien access to such services as health care and schooling, and the proposal of Rep. Duncan Hunter (R) of San Diego for a 14-mile ''triple fence'' along the busy San Diego border. The fence project, criticized by the Border Patrol as a waste of resources, and as ultimately dangerous for Border Patrol agents, received funding in the expanded 1996 budget.
Although the Southwest border strategy is still relatively new, it is showing some signs of success. Apprehensions of illegal border-crossers in the busy Imperial Beach section of San Diego county fell 40 percent in 1995. However, in the first weeks of this year, the San Diego Border Patrol apprehended 51 percent more undocumented aliens than in January 1995. Nationally, deportations of criminal aliens topped more than 51,000 in 1995 and are projected to increase further this year.
Aliens themselves report a harder time getting across what they once considered a porous border. ''I've been stopped eight times just in the past few days, and I'm about to give up for now,'' says Jose Antonio Villalba, a solderer from Sinaloa state in central Mexico trying to get to a job in San Diego. ''I used to just go back and forth, but this is getting rough,'' he says.
That is music to the ears of Johnny Williams, chief of the San Diego Border Patrol sector. ''We want to raise the deterrent factor so that finally people don't try at all,'' he says.
As part of the campaign, the INS also has held press conferences by satellite with Mexican journalists in traditionally high-migration Mexican states. The idea is to get the word out before the annual migration swells in the spring that illegal crossing is more difficult and costly.
Still, many border experts doubt that stepped-up border surveillance and tougher anti-immigration measures can substantially stanch the flow of illegal immigrants into the US.
Frank Bean, a noted demographer at the University of Texas at Austin, says the new policies have curtailed the daily crossings of local Mexicans going to jobs, shopping, or on short visits, but have simply pushed many immigrants to new crossing points.
That thinking is backed up by Border Patrol apprehension statistics that show major increases in remote and desert areas of the border that aliens once left alone. Such numbers prompt the Border Patrol to pronounce its strategy a success. ''No one wants to cross in a desert,'' Mr. Williams says, ''so if our apprehensions are up [in 1995] in Arizona, then we must be doing something right.''
What such numbers tell researchers like Mr. Bean, however, is that people will do what they must to reach a job. ''Job growth in the US over recent years is still the most important factor in increased Mexican migration,'' he says.
The simple truth may be that it is nearly impossible to judge the success of the INS's beefed-up surveillance of the Southwest border - or the efficacy of immigration-control spending that is up 72 percent over three years - by the reams of apprehension figures the INS publishes annually.
With immigration such a hot issue, Border Patrol officials are under pressure to place the most politically favorable light possible on their numbers. Thus the lower figures that many sectors like San Diego or El Paso recorded in some years of this decade were officially attributed to a larger Border Patrol doing a better job of deterring illegal immigration.
But as numbers have risen again in recent months, in some cases dramatically, that too is officially offered as evidence that the higher spending is bearing fruit, because more agents are catching more aliens.
If the border strategy does result in fewer illegal aliens entering the US, one likely result will be criticism of the policy from American employers who need large numbers of low-skill employees for some form of guest-worker program. Already California's farmers, worried about labor shortages, are pushing for something like the national Bracero program in the 1950s to contract with Mexico for seasonal workers.
Meanwhile, the Border Patrol's Stiles will watch the border through his infrared scope. On the same night Pedro is trying to get across, Stiles sings the camera's praises, but also laments the Pacific fog settling in and the way it renders the ojo magico nearly useless.
If Pedro is still out there, this might be his chance.