They're gunning for the big guy.

Prosecutors yesterday filed paperwork that enables them to seek the death penalty against Kermit Gosnell, the abortion doctor charged with murder for the deaths of one woman and seven viable babies born alive in his West Philadelphia clinic.

But three of Gosnell's staffers also accused of killing babies caught a break: Prosecutors filed for a 60-day extension to get more time to mull whether they'll seek executions for co-defendants Lynda Williams, Steven Massof and Adrienne Moton.

The extension suggests that they'll lean on the trio to get more evidence against Gosnell.

Prosecutors filed the notice of aggravating factors, noting that he's accused of multiple murders and that his alleged victims were younger than 12, Assistant District Attorney Joanne Pescatore said.

Attorney Jack McMahon, who represents Gosnell, said that the death penalty "makes no sense."

"He's a 70-year-old man with no previous record," McMahon said. "And Pennsylvania hasn't carried out an execution in years [since 1999]. The reality is, there will be no death penalty for Mr. Gosnell, so why clog up the court system with a death-penalty case that is death penalty in name only?"

The next court date for Gosnell and his co-defendants is a pretrial conference on March 30. Just two of the former doctor's alleged accomplices - Maddline Joe and Tina Baldwin - are out on bail, and both appeared in court yesterday. Neither would comment to reporters.

Gosnell is charged with the first-degree murder of seven viable infants and third-degree murder in the 2009 death of a patient, Karnamaya Mongar, at his squalid clinic, the Women's Medical Society, at 38th Street and Lancaster Avenue.

Gosnell is accused of performing illegal late-term abortions, during which he induced preterm labor rather than use traditional abortion methods. When babies were born alive, according to a grand-jury report, Gosnell and his staffers would slit their throats or stab them in the neck with scissors to sever their spinal cords.