GARDEN CITY, N.Y. » The last of 20 students accused in a college entrance exam cheating ring in an affluent New York suburb surrendered to authorities on Monday.

Michael Pomerantz, 18, and an unidentified teenager turned themselves into Nassau County prosecutors before being taken to district court for arraignment. Pomerantz is one of five current or former students at Great Neck-area public and private high schools charged with accepting payments of between $500 and $3,600 to impersonate other students on SAT and ACT college entrance exams.

A longtime critic of the testing system notes that Nassau County is one of the few municipalities to file criminal charges in a school cheating scandal.

Pomerantz was facing felony charges including scheming to defraud, falsifying business records and criminal impersonation. He pleaded not guilty and was released without bail. His next court date was scheduled for Jan. 5. His attorney did not immediately respond to a call for comment.

Pomerantz and the other four face up to four years in prison if convicted.

Fifteen other students, including one who surrendered Monday, are facing undisclosed misdemeanor charges for having others stand in for them and take the college exams. Prosecutors say they are barred from identifying those 15 because they are being prosecuted as juveniles. Authorities say they can’t even contact the students’ colleges to inform them of the cheating allegations because of privacy laws.

Also Monday, a spokesman for District Attorney Kathleen Rice said that the case against Samuel Eshaghoff, 19, the first of the five students arrested as alleged impostors, was postponed Monday pending a possible grand jury investigation. The spokesman, John Byrne, would not elaborate.

Eshaghoff, a student at Emory University in Atlanta, has pleaded not guilty.

The scandal, which erupted in September, has prompted a review by a state Senate subcommittee on higher education. The panel held a hearing last month where it received assurances from The College Board and Educational Testing Service that a review of security procedures surrounding the tests was under way.

The ETS, which administers the SAT on behalf of the Princeton, N.J.-based College Board, said former FBI director Louis Freeh has been retained to offer recommendations on enhanced security. There was no indication on when recommendations would be made.

Bernard Kaplan, principal at Great Neck North High School is among those suggesting that digital photographs of each student be taken when they arrive to take the exams. Great Neck North is where the scandal first surfaced in the spring after faculty members looked into rumors that students had paid someone to take the SAT for them.

Authorities were particularly dubious after hearing that Eshaghoff allegedly stood in for a female student on one of the exams.

In testimony before the Senate subcommittee last month, Kaplan noted that all proctors require of a student arriving to take a test is a photo ID, "which any fifth grader with a computer can make." He also argues that the current system that allows students to take the SAT at a location other than their "home" school should be abolished.

He said the students implicated in the scandal all went to schools where they would not be recognized by faculty to take the exams. He said about 150 students who don’t attend Great Neck North went to the school on a Saturday in the spring for an SAT exam.

"The others all had some sort of picture ID, but anyone of those could be completely made up or forged, and we would have no way of knowing and neither does ETS. The proctors take a look, it says Joe Schmoe from Hoover High School with his picture and that’s that.

"It is ridiculously easy to take the test for someone else."

Defense attorneys for some of the students have questioned whether the courts are the proper venue for students suspected in the cheating scandal. FairTest, a group critical of standardized testing, "is aware of no other current case in which a district attorney is pursuing criminal charges," said spokesman Bob Schaeffer. He cited a 1992 case in Maryland, where a student was sentenced to six months for having a friend substitute for him on an SAT exam.

A spokesman for District Attorney Thomas Spota in neighboring Suffolk County, on Long Island, confirmed that the prosecutor sent a letter Monday to school administrators in that county seeking any information on suspected cheating, although there was no immediate information that students there had participated in any schemes.

Rice, the Nassau County prosecutor, argues that the students need to be dealt with in the criminal judicial system.

"Educating our children means more than teaching them facts and figures. It means teaching them honesty, integrity and a sense of fair play," she said last week. "The young men and women arrested today instead chose to scam the system and victimize their own friends and classmates, and for that they find themselves in handcuffs."