During 12 days of an ongoing prostitution sting along the Kensington Avenue corridor, 102 people made Santa's naughty list and the Philadelphia Police Department's arrest log, investigators said yesterday.

One man, Ismael Lopez, made it on twice.

After he was arrested Nov. 19 for trying to trade heroin for sex with an undercover cop and for carrying a gun, Lopez, 47, returned to Kensington Avenue within two weeks and made the same offer to a different undercover officer, police said.

"We wanted to let people know that if you're going to come down to Kensington Avenue or any other area in the city of Philadelphia to engage in illegal activity, you may be doing so with an undercover police officer," Lt. Charles Green of the Citywide Vice Squad said.

Police stressed that the sting, conducted by the Vice Squad, the Special Victims Unit and the 24th District, is ongoing.

Green said that while Kensington Avenue has historically been a prostitution-heavy area consistently patrolled by the Vice Squad, this sting was prompted by a recent pattern of four violent physical and sexual assaults committed in that area, police said.

"The girls subject themselves to a lot of danger," Green said. "It's bad enough they're prostitutes but nobody deserves to get their head smashed in, and God forbid an innocent person gets caught up in this."

As prostitutes were taken in and interviewed by police, they were shown a composite sketch of the man responsible for the Oct. 4 rape and beating of a woman. The man may be responsible for three similar assaults in the area, SVU Capt John Darby said.

As for the men, or "Johns," picked up in the sting, swabs were taken of their DNA if they matched the description of the suspect, which more than a dozen did, Darby said.

Of the 102 people arrested in the 12-day operation, 76 were "Johns" and 26 were female prostitutes, Green said.

Nine of those arrested lived outside Philadelphia and many of the city residents who were arrested came from different neighborhoods, he said.