Simpson is in a Nevada prison serving nine to 33 years for a 2008 kidnapping and robbery case in Las Vegas.
His former manager, Norman Pardo, told People magazine Simpson is "a little worried" that the knife issue could in some way affect his parole, but that is his "only fear."
"When he heard the news on TV, all he did was shake his head, as if to say, 'Will this ever end?' He's definitely shrugging it off and pretty much saying, I'm not going to worry about it," Pardo told the magazine.
The sources said preliminary review suggested that the weapon appeared to be unconnected to the brutal 1994 slayings of Simpson's ex-wife, Nicole Brown Simpson, and her friend Ronald Goldman.
It remains to be seen whether DNA of any kind will be found on the knife given how long it has been since it was reportedly unearthed at the Simpson estate.
Simpson was tried for murder but a jury found him not guilty.
The knife was supposedly found while crews were tearing down the Simpson estate in Brentwood after the property changed hands. But the owner of the firm that did the demolition said no one found a knife.
“I think it’s a joke. I think it’s just filler … no one on my crew found anything,” said Mike Weber, 70. “I had instructed my people, ‘If you find anything, don’t keep it. Tell me, we’ll take the appropriate action.’”
The retired Los Angeles police officer given a knife found by the construction worker called the LAPD to report it years ago, his attorney said Friday.
When the department showed no interest, retired Officer George Maycott put it in his toolbox for more than a decade, attorney Trent Copeland said.
The LAPD is investigating whether the knife is tied to the deaths of Nicole Brown Simpson and Goldman and is conducting a forensic examination. Department officials say at this stage they have nothing to tie the knife to the slayings.
Copeland said Maycott, who retired in 1998, was working security on a movie set around 2003 when a construction worker at the demolished estate handed him the knife.
"'Hey look, I found this knife on what I think is O.J. Simpson's property,'" the worker said, according to Copeland, re-creating Maycott's recollection of the encounter. "'It is dirty, muddy and rusted out, but do you guys want it?' ... Within moments of receiving that knife, he called West LAPD Traffic Division."
Copeland said his client was put on hold and later told that the Simpson case was over. He was told, "O.J. Simpson has been acquitted and there is double jeopardy.... There is nothing we can do."
Maycott took the knife home and put it in his toolbox and left it there for more than 10 years, Copeland said. "He thought it had no evidentiary value," the attorney said.
Copeland said his client feels the LAPD is being dragged through the mud.
"He also doesn't want to be portrayed as the villain here, as the bumbling cop who had evidence here and did not do anything with it.... He did ask what he should do with that knife."
Mark Fuhrman, the former LAPD officer involved in the Simpson case, has also weighed in, saying it should be simple to determine if the knife was involved in the slayings.
“It can only be a certain width, length and thickness, or it simply isn’t the weapon,” he told Fox News. “The autopsy results, especially on Ron Goldman, were very specific.”