Lehigh County's top prosecutor is facing his first challenger in 12 years, and District Attorney Jim Martin's opponent is making some serious allegations against him. 

Democrat Ed Koren's television ad pulls no punches against Martin, claiming the D.A. dropped the ball on two high-profile cases.

"His negligence allowed convicted murderer Michael Ballard to be released, who then ruthlessly killed four more people," an announcer said in the ad.

Ballard killed four people last year while out on parole for a previous murder.  Four years earlier, Martin had a chance to object to Ballard's release, but admitted his office never responded to a letter from the state corrections board.

"We checked our file," Martin said.  "We could find no response to that 2006 letter."

"We didn't do anything," said Koren, his challenger, "and in the end, we know the end result."

Martin said that's not the whole story, though.  After Ballard's initial release, he went back to prison for a parole violation.

"He violated his parole and was reincarcerated," said Martin. "And he was again paroled in 2009.  In 2009, we were not put on notice of his pending parole."

Koren also brought up another case in his TV ad.

"When state police wanted to prosecute infamous mass murderer Charles Cullen, Martin again refused," said the ad's announcer.  "Cullen went on to kill 22 patients in New Jersey."

Cullen is a nurse suspected of more than 40 patient deaths.  He pleaded guilty to 13 murders in New Jersey and several more in the Lehigh Valley.  Nurses at St Luke's brought their concerns to Martin in 2002.

"Early on, the nurses came to him and told him there was a problem," said Koren.

Martin never charged Cullen.  He said, after months of investigating, medical experts could not come up with enough evidence.

"We had no autopsies. We had no toxicology results," said Martin. "We had patients who were severely medically impaired to begin with."

Beyond both cases, Martin said the race comes down to the experience.  He hasn't had an opponent in 12 years, something Martin believes speaks for itself.

"I've been doing this job for 14 years; I think, doing it well," he said.  "My record and the record of this office indicates that."

Although Koren has never worked as a prosecutor, he has decades of law enforcement experince.  Koren is a former Secret Service agent, Allentown police officer, and state police lieutenant.  Koren said his experience as a cop gives him an edge on getting ahead of the Lehigh Valley's growing gang problem.

"Really, a proactive type posture rather than always having to come from the back and work forward," he said.

Koren wants to look at creating drug and veterans' courts.

"The goal always of the system is to keep people, as many people, away from prison as possible," he said, "because most people don't come out of prison any better than they went in, and a lot of times they come out worse."

Meantime, Martin points to 171 murder convictions under his watch.

"We have a better than 97 percent conviction rate over those 14 years," he said.

In spite of that, Koren claimed the D.A. has gotten cozy with defense attorneys.

"It seems more and more, we're giving away a lot of the more serious charges just to get a plea bargain," Koren said.

"That's nonsense," countered Martin.  "Any plea agreement that has been entered into in the last 14 years has been carefully evaluated."