Sgt. Olivia Benson (Mariska Hargitay) and the team are working a familiar suspect as “Law & Order: SVU” opens its 17th season.  

In the episode “Devil’s Dissections,” the body of a young woman is discovered floating in the waters of Pelham Bay, and it immediately appears to be the work of serial killer Gregory Yates (Dallas Roberts).  

But how could it be?  Yates — a former doctor who liked to torture his victims — has been a guest at the Green Haven Correctional Center since being found guilty of murder in last season’s finale.  He is busy preparing an appeal.

“Either we missed one or Yates has a copycat,” Liv declares.  And the investigation is underway.

The bureau is short-handed as Detective Amaro (Danny Pino) has relocated to Laguna Beach, California.

Rollins begins by paying a visit to Green Haven where she tells Yates that Medical Examiner Carl Rudnick has found traces of green nail polish (his calling card) on the new victim.

Still, the timeline seems too tight for Yates to have committed the crime — and something doesn’t quite add up as his victims were all brunettes and he has never completely dismembered a body.

The body is ID’d as Brooke Groves, but when Liv and Carisi (Peter Scanavino) visit her home, they learn the deceased is actually Brooke’s alcoholic and drug-addicted identical twin sister, Rachel.

Rachel was last seen leaving a homeless shelter several years earlier with a woman thought to be her mother — but, of course, it wasn’t. 

Back at the jail, Yates offers up some interesting information:  more than a decade ago, he was asked to visit the home of a colleague who needed stitches but was too embarrassed to go to the hospital.

That other doc, Yates said, had been in some sort of scuffle with a woman who was not present when he arrived.  Yates floats the idea that this doctor could be hiding something.

When the team arrives at the home (which now has a new owner) they discover a suitcase sealed inside wall.  It contains the mummified corpse of a young woman who was thought to have left the country.

The body had been dissected in the same way as Rachel Groves.  But if Yates was appealing his conviction, why tip off the team to another victim?

“He’s sick, but not stupid,” Rollins reminds everyone.

Yates says he knows the killer, trades that information for a conjugal visit with his fiance, Susie Frain (Mary Bacon), then reveals that the crime was committed by (drumroll…) medical examiner Rudnick.

“He never liked people, but he always liked cutting,” Yates says.

Rudnick is arrested after detectives find a photo of the corpse and a closet full of women’s clothing and wigs at his home.  He is released on $2 million bail.

A different M.E. is called in and confirms that Rudnick has been fudging his reports and stealing the victims identities — and that the suitcase girl was dismembered while still alive!

Susie tells the detectives that she has a photograph that can blow the case wide open, but hours later — with Rudnick’s whereabouts unknown — she is found dismembered and floating in the water as well. Yates reveals Susie may have been pregnant.

Rednick flees, dressed as a woman, but the SVU squad tracks him down in Buffalo and returns him to New York City for trial.

When Rollins next returns to Green Haven, Yates correctly figures out that she is pregnant.  She eventually tells Liv, but asks that the information not be made public yet.

Back in court, Rudnick has an almost water tight alibi, but the tide turns when Carisi discovers a video in which he is caught confessing to the murders.

Rudnick changes his plea to “guilty as charged” to the murders of Rachel Groves and Susie Frain, but ADA Barba (Raul Esparza), in a sly maneuver, drops the murder charge for the woman found in the wall.

This news seems to bother Yates, who then confesses to Rollins that Rudnick had enlisted him to help with the murder.

“I believe when one life ends another begins,” he tells her, justifying the admission.  “You are bringing life into this world, just as I lost my life and my child.  I feel a connection to you.”

In the episode’s final scene, the two killers are reunited in the jailhouse cafeteria.  “We have a lot to catch up on,” Rudnick notes.