In an interview with NBC10 in Philadelphia, a former prosecutor explained why he didn’t charge Bill Cosby will sexual assault in 2005 even though he thought Cosby “did it.”

“At the time I remember thinking that he probably did do something inappropriate,” said Bruce Castor, a former district attorney in Montgomery County, Penn. “But thinking that and being able to prove it are two different things.”

As NBC reported, a former Temple University employee said Cosby drugged and sexually assaulted her in 2004 in his home in Cheltenham, Pa.. Castor, now a county commissioner, explained the difference between thinking someone is guilty and charging him.

“I didn’t say that he didn’t commit the crime,” Castor said. “What I said was there was insufficient, admissible, and reliable evidence upon which to base a conviction beyond a reasonable doubt. That’s ‘prosecutors speak’ for ‘I think he did it but there’s just not enough here to prosecute.'”

The urge to prosecute the famous comedian was strong, Castor said, but he had to resist.

“As much as I wanted to go forward, there wasn’t enough evidence and prosecutors are bound by the law,” he said. “I mean, I’m not a fool. I recognize that had I arrested Bill Cosby it would’ve been front page news at every newspaper in the world and led every broadcast in the world. In my position that’s something that might be of value to me.”

Castor also said the alleged victim’s delay in speaking out hurt the case.

“You lose the ability to test for blood or intoxicating agents, whether she was drugged,” he said.

Andrea Constand, the Temple University employee who made the accusations, settled a civil suit with Cosby in 2006. Earlier this week, Constand’s attorney spoke out after Cosby’s attorney posted a statement about sexual assault charges leveled at the comedian.

“Over the last several weeks, decade-old, discredited allegations against Mr. Cosby have resurfaced,” John P. Schmitt, Cosby’s lawyer, said in a statement, which has been removed from “The fact that they are being repeated does not make them true. Mr. Cosby does not intend to dignify these allegations with any comment. He would like to thank all his fans for the outpouring of support and assure them that, at age 77, he is doing his best work. There will be no further statement from Mr. Cosby or any of his representatives.”

The statement didn’t stay up long. It was quickly replaced with one that addressed Constand’s case directly.

“The statement released by Mr. Cosby’s attorney over the weekend was not intended to refer in any way to Andrea Constand,” read a joint statement issued by Schmitt and Dolores Troiani, Constand’s lawyer. “As previously reported, differences between Mr. Cosby and Ms. Constand were resolved to the mutual satisfaction of Mr. Cosby and Ms. Constand years ago. Neither Mr. Cosby nor Ms. Constand intends to comment further on the matter.”

Here’s the NBC story.