In an age when built-in laptop cameras, no larger than a fingernail, have become commonplace, using them for clandestine surveillance can be a matter of simplicity itself.

Doing so requires one technical tweak to the machine before it is turned over to its user.

First, the computer's administrator would have to enable the laptop to respond to remote access. Once the laptop is connected to the Internet, the administrator could sign on to it without the user knowing.

Then the administrator, over the Internet, could turn on the laptop's camera and microphone as easily as if the machine were in the same room, and record the data - digital audio and video, for example - to the administrator's machine.

"I could take over without the user's knowledge and just activate the webcam," said Jim Martin, who is based in Houston and teaches computer forensics to law enforcement and private industries.

This is not always a bad thing, as illustrated by the case of a White Plains, N.Y., woman who in May 2008 found that her stolen MacBook was showing up online. She switched its camera on remotely and soon had a picture of its suspected thief to take to police, according to the New York Times.

But the alleged monitoring of a Harriton High School sophomore via a school-provided MacBook is more troubling, experts said.

"I truly hope this turns out to be an urban myth," said David Dwyer, an educational technology professor at the University of Southern California.

There was even said to be an ideal cover story that got students to disregard a key warning.

Although a tiny green diode lights up when the MacBook's iSight camera, mounted just above the screen, is recording, school administrators allegedly warned about a bug - well-documented online by other MacBook users - that made the light come on randomly.

"Based on the number of times the green lights have randomly triggered," Lower Merion student Brian Sperling posted on the technology Web site Gizmodo yesterday, "I can't imagine that we're being watched (they'd need a task force) but some of the time [it] could have been them."

An Apple spokesman in Cupertino, Calif., declined to comment.

Widener University law professor Stephen Henderson said yesterday that unauthorized surveillance with a laptop camera would violate wiretap laws - even if being used to identify a suspected computer thief.

He called the idea of watching a student at home with a laptop camera "not only illegal but unbelievably callous and stupid" if true.

"We can't accept them losing sight at the end of the day they are teaching our students to be good citizens," Henderson said.