NEW YORK, JAN. 10 -- When six Harlem youths were arrested last April in the brutal beating and rape of a female jogger in Central Park, prosecution and conviction seemed almost a foregone conclusion.

While the investment banker clung to life in a Manhattan hospital, the teenagers gave police written and videotaped confessions of their involvement in the late-night "wilding" attack.

In a typical statement, Kharey Wise, 17, told police that his friends had "slapped and punched her in the face . . . hit her in the face with a rock . . . . Blood was scattered all over the place." He said that "I had to get into it too. I had to do what they were doing. They were on top, raping her, and I was playing with her."

But as the case has slogged through months of pretrial hearings, the prosecution's task in proving attempted murder, rape and sodomy has grown more difficult.

Defense lawyers are moving to have the confessions thrown out on grounds of coercion. Genetic tests on semen taken from the jogger's body and clothing were inconclusive. The six teenagers are likely to be tried separately, which would make it more difficult to present corroborating evidence.

If Manhattan Supreme Court Judge Thomas B. Galligan grants defense motions to exclude the confessions when he rules next month, it would eliminate the core of the prosecution's case because there are no independent witnesses. The jogger, 29, has returned to work at Salomon Brothers and is willing to testify but cannot recall the attack.

Colleen Roche, spokeswoman for Manhattan District Attorney Robert M. Morgenthau, said that "the statements were not coerced. They were taken in accordance with the juvenile laws," which require that a parent or guardian be present during police questioning of those under 16.

But Howard Diller, an attorney for Kevin Richardson, 15, said the youth's mother had recovered from a stroke, was "really out of it" and did not understand when police said her son had the right to remain silent.

"The coercion was the promise to go home," Diller said. "There was a long period of time where he was without anything to eat or drink . . . . He's not bright by anyone's standards. He was conned into making the statements."

Wise testified in November that, during questioning, a detective "threw his hand across my face, slapped me." The detective denied this in court.

Wise's lawyer, Colin Moore, said in an interview that the youth "was scared. They literally forced him -- he made three or four different confessions. They wrote out the statements for him . . . . They induced him into making incriminating statements with the promise that he'd get some reward, get to go home to his mother."

One defense lawyer argued that the grandmother of Raymond Santana, 15, did not understand the proceedings, despite police testimony that the Miranda warning was translated into Spanish for her.

Another said Yusef Salaam, 15, should not have been questioned without a guardian, but police said he produced identification saying that he was 16 and therefore not subject to juvenile law.

Another complication is that several defendants minimized their role in the attack. Antron McCray, 15, said he simulated raping the jogger "so everybody {would} just know I did it."

The genetic tests were inconclusive because the semen samples were insufficient or too degraded for identification to be made, according to an FBI report. Prosecutors call the results a wash, but Moore said they "conclusively establish that none of the defendants who have been charged had anything to do with the crime."

The tests identified semen from the jogger's clothing as belonging to her boyfriend, which prosecutors attribute to previous sexual contact. But Moore seized on the finding to urge Morgenthau's office to investigate the boyfriend, although Moore acknowledged that there was no evidence that the friend was in Central Park that night.

He compared the prosecution to the recent Boston case in which a black man was blamed for the murder of a pregnant woman apparently killed by her husband.

Moore said the defendants are being framed "because they're black and Hispanic, and they're very young kids."

Defense lawyers say prosecutors cannot obtain the testimony they need without striking a plea bargain. "I think a deal is ultimately going to be made with one of the six kids," Diller said.

Jermaine Robinson, 15, is believed to be cooperating with prosecutors after pleading guilty to first-degree robbery in an attack on a male jogger in the park the same night. A 14-year-old arrested during the rampage also is expected to be a prosecution witness.

Although the female jogger suffers from post-traumatic amnesia, Diller said her testimony could have an emotional impact on the jury because "she is an extremely sympathetic person and pathetic soul and the whole world would love to see her."

Wise and Santana are still being held. The other four are free on bail, some with funds raised by the Rev. Al Sharpton, a spokesman for Tawana Brawley when she made claims of abduction and rape later discredited by a state grand jury. Wise's bail is $50,000.

As juveniles, five of the youths face maximum penalties of five to 10 years in prison if convicted. Wise, subject to adult penalties, faces 16 2/3 to 40 years in prison.