A bungling techie in the Brooklyn District Attorney's Office accidentally erased an audiotape recording of a statement by one of the men charged in the death of NYPD Officer Russel Timoshenko, The Post has learned.

There were no other copies of the cassette, made July 12 by detectives as they grilled Robert Ellis at the state police barracks in Swiftwater, Pa., said sources familiar with the case.

It's the second major snafu associated with the high-profile case and the latest in a laundry list of legal lapses for DA Charles Hynes in the past year.

The shocking mix-up came to light at a routine court appearance last month, as lawyers discussed what evidence the DA will hand over to the defense.

“The tape was recorded over with 911 calls associated with this case . . . I would like to know the circumstances on a [first-degree murder] case that any 911 tape was taped over my client's initial statement,” defense lawyer Danielle Eaddy told Judge Plummer Lott, according to court transcripts.

DA spokesman Jerry Schmetterer noted that his office brought the mishap to the court's attention as soon as it became aware of it.

“It was human error,” he said. “It has absolutely no effect on the case. We have sufficient evidence against this defendant, and we are proceeding to trial.”

Detective Peter Margraf used a tape recorder borrowed from the Pennsylvania State Police to “preserve” Ellis' statement.

What's left now are the detectives' notes of what he said, plus an intact videotape of a separate statement.

Timoshenko, a rookie cop, was shot dead July 9, after he and partner Herman Yan pulled over a BMW SUV in Crown Heights. Prosecutors allege that Ellis, 34, firing from the front passenger seat, hit Yan in the arm, while Ellis' buddy Dexter Bostic, 35, shot Timoshenko in the head from the back seat.

In October, The Post reported how NYPD crime-scene investigators missed a bullet fragment inside the BMW.

Eaddy scoffed at the prosecutors' claim that the lost material is covered in the notes and video.

“Something could have been said, something overheard,” she said.

Trial lawyer Ron Kuby said the DA might now have to make the tape tech testify.

“They would be well advised to put the poor schlub on the witness stand, so they can say to the jury, 'You heard this man, he explained what happened, and he feels as bad about this as anyone,' ” he said.