All of the fumbling of evidence, by LAPD, opened avenues for reasonable doubt. Including the avenue: LAPD detectives corrupting, forging, nudging the evidence.
Plus, the following, did not help the prosecution:
Thursday, September 7, 1995:
Roanoke Times / AP
Detective Mark Fuhrman was called back to the witness stand Wednesday [09/06/1995] and was asked point blank whether he planted evidence against O.J. Simpson. He refused to answer, invoking his Fifth-Amendment right against self-incrimination.
Forensics at the OJ Simpson Trial
Evidence Collection
From the beginning, there were issues involving evidence collection. An important bloody fingerprint located on the gateway at Nicole Brown's house was not properly collected and entered into the chain of custody when it was first located. Although it was documented in his notes by Detective Mark Fuhrman, one of the first to arrive on the scene, no further action was taken to secure it.
The detectives who took over Fuhrman's shift apparently were never aware of the print and eventually, it was lost or destroyed without ever being collected. Other items of evidence were also never logged or entered into the chain of custody, which gave the impression that sloppy forensic collection had been carried out at the scene.
Securing the Evidence
Throughout the investigation, there were issues with how evidence was secured. There was about 1.5 mL of O.J. Simpson's blood assumed missing from a vial of evidence. The LAPD could not counter the idea of "lost blood" because there was no documentation of how much reference blood was taken from Simpson as evidence. The person who drew the blood could only guess he had taken 8 mL; only 6 mL could be accounted for by the LAPD.
To add to the problem, the blood was not immediately turned over as evidence but was carried around for several hours before it was entered into the chain of custody, allowing for speculation of when and how the 1.5 mL of blood may have disappeared.
The security of LAPD storage and labs was also brought under scrutiny when it was discovered that some pieces of evidence had been accessed and altered by unauthorized personnel. Simpson's Bronco was entered at least twice by unauthorized personnel while in the impound yard; Nicole Simpson's mother's glasses had a lens go missing while it was in the LAPD facility.
OJ did it. The blood evidence against him could not have been faked. IIRC, it included the form a near microscopic aerosols that only occur when a LOT of blood is being violently splashed in and about.
There is no evidence of “lost blood”. The defense argued for it and LAPD did not document the exact amount taken, so they could not prove none was missing. But neither did the defense show 1.5mm of blood WAS missing.