What role did the physical evidence play in the O.J. Simpson investigation case?

The physical evidence discovered during the investigation of the murders of Nicole Brown Simpson and her boyfriend, Ron Goldman, was the hinge on which the outcome of the O.J. Simpson trial swung. The evidence was pivotal to the arguments of both the prosecution and the defense, because, although the evidence itself was merely a collection of facts, the opposing sides interpreted it in very different ways.
Strands of hair were found on the victims' clothing. These hairs microscopically resembled Simpson's hairs.

Carpet fibres consistent with those from Simpson's car were found on the infamous bloody glove connected with the murders.

Blood was found in multiple places: outside the victims' residence, inside Simpson's car, on Simpson's driveway, inside Simpson's house, and on Simpson's socks. The blood outside the victims' residence was DNA tested and proven to be Simpson's blood. The blood on the socks was DNA tested and proven to be Nicole's. The blood inside the Bronco and inside Simpson's house contained DNA from Simpson and both victims.

The glove which was found outside Simpson's house was also soaked in blood and contained DNA from Simpson and both victims.
The prosecution's case combined this physical evidence with witness statements concerning Simpson's behavior on the night of the murders, the abusive nature of his marriage to Nicole (including audio from 911 calls Nicole made during incidents of domestic violence), and Simpson's flight from the city after the murders. The prosecution presented all of the above as proof that Simpson had committed the murders.
The defense's case took its lead from the prosecution and responded to each new point of evidence by challenging, not the evidence itself, but the manner in which it was collected. Their argument was that the investigation was compromised by racial bias on the part of the LAPD, that the chain of custody for various pieces of evidence was unclear, and that, in fact, much of the evidence had been planted during the course of the investigation in order to frame Simpson. The evidence was largely circumstantial, so the outcome of the trial depended upon which argument the jury chose to believe.
The lynchpin of the trial was the bloody glove. This was meant to be the prosecution's ace-in-the-hole: the glove itself was custom-made and the prosecution were able to prove that Nicole had ordered two pairs of these gloves during her marriage to Simpson, one for him and one for herself, so there was strong reason to believe this was Simpson's own glove. DNA evidence proved it was soaked in the victims' blood, and some of Simpson's own blood was also present. The glove was found outside Simpson's home, as if it had been dropped there. The prosecution argued that this piece of evidence was incontrovertible, and proved that Simpson had committed the murders.
The defence contended that the glove had been planted by the LAPD to frame Simpson, and although the glove was custom-made, that did not prove it had been made for Simpson. They demanded they be allowed to prove their point to the jury by having Simpson put on the glove in open court. As it was custom-made, they argued, it should fit Simpson's hand perfectly, leading to the now-famous argument, "If it doesn't fit, you must acquit." The glove did not, in fact, fit onto Simpson's hand during the demonstration, and this factor swayed many jurors to acquit Simpson for the murder charges, although there are factors that would explain why the glove didn't fit during the trial.
https://en.wikipedia.org/wiki/O._J._Simpson_murder_case

https://famous-trials.com/simpson/1857-evidence