D4vd Murder Case: Private Investigator Kicked Out of Court

A private investigator connected to D4vd's case was kicked out of the courtroom during the preliminary hearing ... and apparently it's because he might end up being a witness in the potential murder trial.

Here's the deal ... the private eye was booted from the courtroom Thursday after prosecutor Beth Silverman pointed out to the judge that he was present during grand jury testimony -- and could be called as a potential witness somewhere down the line.

Potential witnesses -- besides alleged victims like Celeste Rivas' family -- are barred from the preliminary hearing ... so the judge ruled this dude had to go.

Silverman also apparently tore into Celeste's family attorney Patrick Steinfeld for speaking with this person ... though Steinfeld and the P.I. told the judge they didn't realize they were violating any rules by conversing.

The private eye told the judge he didn't even know who Steinfeld was during their conversation ... while Steinfeld said he didn't realize the other man could eventually be a witness.

Silverman scolded Steinfeld ... threatening to pull the badge allowing him in court in the future if he violated her rules again.

This week has been a difficult one in court ... especially for Celeste's fam, who have had to listen to prosecutors describe the allegations against D4vd in graphic detail.

Among the claims made in court this week ... D4vd's Tesla was loaded up with air fresheners when Celeste's body was found in it, and a forensic expert says possible blood stains were found all over D4vd's garage, where he allegedly dismembered her body.

Steinfeld spoke to us outside the courthouse on Wednesday ... saying Celeste's family simply couldn't understand why the singer would allegedly use a chainsaw on their daughter.