Citing law enforcement sources, NBC is reporting that a utility-style knife apparently recovered from O.J. Simpson's former house is inconsistent with the weapon used in the 1994 stabbings of his ex-wife Nicole Brown Simpson and her friend Ron Goldman, in which Simpson was acquitted of murder charges.

The sources described the knife as a relatively inexpensive, smaller-bladed utility knife typically carried by construction workers, gardeners and other laborers, NBC reported.

The murder weapon had not been recovered at the time of his sensational trial. A medical examiner testified for the prosecution at the time that Brown Simpson and Goldman were likely slain with a single-bladed, six-inch knife.

The utility knife was supposedly found by a citizen, possibly during demolition of the home years ago, and turned over to a now retired police motorcycle officer who was working as a filming location security guard, police Capt. Andy Neiman said.

The knife came to light in the last month, but Neiman did not say how that occurred and declined to elaborate on the timeline of when the knife was recovered. He stressed that the authenticity of the story was not confirmed.

OJ Simpson

O.J. Simpson was acquitted in 1995 of murdering his former wife, Nicole Brown Simpson, and her friend, Ronald Goldman, in Los Angeles. He is now in prison on a 2008 armed robbery conviction related to the robbery of two sports memorabilia dealers. (Julie Jacobson/Associated Press)

"Maybe the story is bogus from the get-go," he said.

He declined to name the retired police officer or to say why the knife had been given to police only in the past two months.

"I would think that an LAPD officer, if this story is accurate as we are being told, would know that any time you come into contact with evidence that you should and shall submit that to investigators," Neiman said. "I was quite shocked."

Police are looking into whether criminal charges could be filed against the officer who held onto the knife, Neiman said, adding that any officer who comes into contact with evidence is required to turn it over to investigators in all circumstances.

He appealed directly to the individual who found the knife: "We would love to have you contact our robbery homicide division."

The knife is being analyzed by a Los Angeles Police Department crime lab. Neiman said investigators didn't know the identity of the person who handed it over and asked him or her to come forward.

The weapon used in the killings has been a mystery for decades.

The killings on June 12, 1994, led to the "Trial of the Century" in which the former football star was acquitted in October 1995 by a jury that deliberated only four hours.

In 1997, a civil court jury found Simpson liable for the slayings and awarded millions of dollars in damages to families of the victims.

Neiman did not believe that Simpson could be charged again with murder if the knife is linked to the killings, citing double jeopardy.

'More questions'

"I'm not an attorney, but it's my understanding from being a police officer for nearly 30 years that double jeopardy would be in place here," he said.

Loyola Law School professor Laurie Levenson, a former federal prosecutor who is a longtime observer of the Simpson case, agreed.

"If they were going to find this knife and make it useful in the murder trial they should have found it 20 years ago, and they didn't," she said. "It will just raise more questions about the incompetence of the investigation and probably lead to more books and more movies."

Fred Goldman, father of victim Ron Goldman, declined to discuss this latest turn in the case.

"He doesn't feel he has much to say at this point. He wants to wait until he knows more," Goldman's wife, Patti Goldman, said during a brief phone interview.

Simpson's Brentwood mansion was torn down after he moved to Florida following his acquittal.

Simpson, who has always maintained his innocence in the killings, is now serving a sentence of nine to 33 years in a Nevada prison for a 2007 armed robbery and kidnapping conviction in which he tried to retrieve football memorabilia. He is eligible for parole next year.

Lawyer questions chain of custody

His Las Vegas lawyer said he had not talked to Simpson about the knife but questioned who was in possession of it over the years.

"The only thing I've heard is that some cop claims some other guy claims he found a knife on some property," attorney Malcolm LaVergne said. "From what I can see, there's no chain of custody."

Simpson becomes eligible for parole in 2017. If the knife turns out to be linked to him, that fact could be raised at his hearing.

"The Nevada Parole Board may consider and give relevant weight to any evidence that bears on whether the release of the petitioning inmate could constitute a danger to the public," the state attorney general's office said in a statement.

News of the knife's discovery was first reported by TMZ.

The new mystery surrounding the knife surfaced just as a popular new FX cable television drama series, The People v. O.J. Simpson, chronicling the sensational trial, is airing. It debuted on Feb. 2.

In addition, an ESPN cable TV biographical documentary, O.J.: Made in America, premiered in January.

With files from Reuters and CBC News