Detectives on catching serial killer Charles Cullen

One of the two detectives who broke the case of serial killer nurse Charles Cullen tells Steve Kroft that Somerset Medical Center, where Cullen was finally caught after administering fatal doses of medication to at least 13 patients there, lied to him and failed to help his investigation. Kroft also obtained a tape of a phone call on which the hospital was urged to contact police but waited three months while Cullen killed five more of its patients.

The detective, Timothy Braun, appears in his first interview and Dr. Steven Marcus, director of N.J. Poison Control, whose urgings to contact police were ignored by Somerset Medical Center, also speaks in his first interview for Kroft's report. The story, with the first television interview with Cullen -- one of the most prolific serial killers in U.S. history -- will be broadcast on 60 Minutes Sunday, April 28 at 7 p.m. PT/ET.

Braun, now retired from the Somerset County Police Department, tells Kroft he did not get much cooperation from Somerset Medical Center. "[The hospital] were very helpful by answering court-ordered subpoenas. That was the extent of their cooperation," says the retired detective sarcastically. When he and his partner asked for computerized records from its drug dispensary system, the hospital said they did not exist back far enough, a claim refuted by the system's manufacturer. "They lied to you?" asks Kroft. "Yes they did," replies Braun.

Asked whether Somerset Medical Center had obstructed his investigation, Braun says, "They didn't try to help it, that's for sure."

Three months before the hospital contacted law enforcement, Somerset Medical Center Director William Cors was speaking with Dr. Marcus on the phone about the suspicious deaths at his hospital. Dr. Marcus urged Cors to contact the police then. He taped his conversation in which Cors says, "What we're wrestling with is...throwing the whole institution into chaos...versus responsibility to protect patients from further harm," he says on the tape. "We have been trying to investigate this ...before we made any rush to... judgment."

In the three months between that conversation and the call to authorities who quickly solved the case, five patients were killed by Cullen. "Those five deaths...I'll remember them for the rest of my life," Dr. Marcus tells Kroft.

60 Minutes will also broadcast a portion of Cullen's taped confession for the first time.