It's not known when the knife was discovered or whether it is related to the 1994 deaths of Nicole Brown Simpson and her friend Ronald Goldman, according to Los Angeles police spokeswoman Norma Eisenman.
The knife was found on Simpson's former estate in the Brentwood area of Los Angeles
The weapon used in the stabbing deaths was described as a long, serrated knife. It was never found.
http://edition.cnn.com/2016/03/04/us/oj-simpson-property-knife/index.html
Though apparently the knife was kept by a retired cop as a souvenir after a construction worker gave it to him years ago... yet he didn't bother to report it then.