For the second time in less than a year, a New York City cop faced rape charges, and while a jury convicted Michael Pena on Tuesday of the most serious sexual assault counts, it got hung on rape charges Wednesday and the judge officially declared a mistrial. New York Juries apparently really don't like convicting cops of rape.

The latest trial is a different situation from the acquittals of Kenneth Moreno and Frank Mata, who were accused of raping a drunk woman they helped home while on duty in 2009, but in both cases the jury decided to convict on some counts but not on rape. In the latest case, Officer Michael Pena was accused of raping a Bronx schoolteacher at gunpoint while he was off duty in 2011. He admitted to assaulting her, but insisted he didn't rape her, and he convinced enough jurors that they couldn't come to a decision and the case becomes a mistrial. He still faces up to life in prison for three counts of predatory sexual assault. Pena was also convicted of three counts of a criminal sexual act in the first degree. With Moreno and Mata, a woman they helped home from a bar said Moreno had raped her in her bed while Mata stood watch, and a jury convicted the pair of official misconduct since Moreno admitted to lying in bed with the woman.

So far, we haven't seen any announcements for the kinds of protests that followed Moreno and Mata's trial (probably because Pena will still be going to prison for a good long time) but still, what does a prosecutor have to do to win a rape case against a cop in this town? More than they have so far, that's for sure.

Update (4:23 p.m. EDT): The Manhattan District Attorney's office took issue with last line of our story, calling it unfair because the charges on which they won a conviction, three counts of predatory sexual assault, are actually more serious than rape. "To say the prosecutor didn’t win this conviction was just wrong," DA spokeswoman Erin Duggan said. Predatory sexual assault is a Class A felony while rape is a Class B felony. In Pena's case, he was convicted of predatory sexual assault because he forced himself on his victim at gunpoint. "Predatory sexual assault is different," Duggan said. "He assaulted anally, vaginally, and orally. The vaginal attack is what was hung up in the jury." Predatory sexual assault is a relatively new term, introduced in 2006 as a way for prosecutors to charger offenses beyond rape. Each charge carries a sentence of 25 years to life.

There's another wrinkle: The New York Times pointed out in its story on Tuesday that one of the jurors, Lloyd E. Constantine, was a law partner of Richard Arbon, who ran against District Attorney Cyrus Vance in 2009, and that Constantine had played tennis with Vance. Constantine was allowed to stay on the case after he assured the judge he was impartial and Pena's lawyer, Ephraim Savitt, did not object to his staying on.