As the Long Island SAT cheating scandal widens, the education community is asking fresh questions about how many students are scamming their way through the most important test they'll take in high school.

And the two organizations that oversee the SAT, the College Board and ETS, are facing fresh scrutiny over whether their security measures are up to snuff.

The soul-searching and finger-pointing are fiercest in Nassau County, New York, where 20 current and former students have been arrested in the exam scam. Prosecutors say that five test-takers used bogus school IDs to take the SAT or ACT for 15 students, who paid between $500 and $3,600 for the privilege.

The test-takers are charged with scheming to defraud, falsifying business records and criminal impersonation. If convicted, they could serve up to four years in prison.

The College Board and ETS have strongly condemned the attempted corner-cutting. "No one despises cheating more than the College Board and the people who design the SAT," said its president, Gaston Caperton, at a recent New York Senate hearing on the controversy.

Declaring its determination to root out cheating, the College Board has hired a security firm headed by former FBI chief Louis Freeh to review its SAT security protocols.

ETS, which administers the exam for the College Board, has indicated that it is open to any reforms Freeh's firm proposes. The organization already has an extensive anti-cheating system in place, spending about 10% of its $225 million annual budget on security, ETS president Karl Landgraf testified at the hearing.

Even as they put their security protocols under the microscope, both the College Board and ETS say they're confident SAT cheating is exceedingly rare -- and that impersonation schemes like the one that allegedly took place on Long Island are even rarer.

Of the 2 million-plus SAT tests taken in any given year, approximately 4,000 scores are canceled because of suspected cheating, according to Landgraf. Of those, 200 to 300 are impersonation cases, he said.

Several hundred additional students -- about 700 last year -- are turned away at the door each year because of questionable IDs, ETS spokesman Tom Ewing said.

But some question whether the numbers are low because many impersonators escape detection altogether.

"All they can say is they are unaware of a large number of impersonations," Bernard Kaplan, the principal of Great Neck North High School, the epicenter of the cheating scandal, said at the hearing.

Though nobody knows how many impostor test-takers get away with it, cheating experts say the number is likely modest.

"It's a small tip of a small iceberg," said Bob Schaeffer, the public education director of testing watchdog FairTest, referring to the arrests on Long Island and the underlying problem they indicate.

He said SAT cheating cases more often involve copying or prior knowledge --- for instance, schemes in which students in one time zone, who have taken the test, pass answers to students in another time zone who haven't.

Undetected impersonation cases probably account for less than 0.1% of SAT tests taken, according to John Fremer, a former ETS official who now runs Caveon Test Security.

From a security standpoint, the test's Achilles' heel is its acceptance of school IDs as a valid form of identification, say principals and test-site administrators.

"Any fifth-grader with a computer" can crank out a fake school ID, Kaplan said at the hearing.

The SAT-takers arrested on Long Island are accused of doing just that. They accessed test sites by flashing doctored school IDs, which showed pictures of themselves alongside their clients' personal data, prosecutors say.

At least one suspect on Long Island is accused of taking the test using a school ID that identified him as female.