Karen Read Juror Says He Felt She Was Innocent

Forget reasonable doubt, one of the jurors who voted to acquit Karen Read of a murder charge in her retrial says he felt she's completely innocent.

Juror No. 4, a man named Jason, joined us on "TMZ Live" Thursday and we asked him what the feeling was like on the jury ... did they vote not guilty because of reasonable doubt, or due to a belief she was innocent?

Jason tells us he doesn't think Karen even hit her then-boyfriend, Boston police officer John O'Keefe, with her car ... as prosecutors claimed. He pointed out that jurors were shown video where Karen's taillight was working just fine after the alleged collision.

It's interesting ... with Jason saying Karen was totally innocent, that would mean someone else was responsible for John's death ... but Jason says he has no clue who that could be and he doesn't know how John died.

There are a lot of conspiracy theories about the trial -- Karen's defense claimed she was framed by John's cop friends -- and while Jason says there were plenty of holes in the police investigation, it's hard for him to say if those holes were deliberate or not.

John told us there was some initial division among jurors ... some felt she was innocent, others said there was enough reasonable doubt, some were unsure, a few thought she was guilty ... but after deliberations, they voted to acquit her of second-degree murder.

Karen was also acquitted of motor vehicle manslaughter while driving under the influence and leaving the scene of a collision that caused O'Keefe's death ... and she was convicted of operating under the influence of alcohol.

Jason said it was hard for prosecutors to prove there was even a collision involving Karen's car and John ... and he says all the holes in the investigation convinced the jury to vote to acquit.

The jury initially said they had a verdict, then recanted and came back with the verdict 15 minutes later ... and Jason tells us what happened -- it was all about the OUI charge.

Karen's case got tons of national attention, and there were throngs of supporters outside the courtroom ... and Jason says he didn't like all that fanfare, because it made his job harder.