D4vd Stone-Faced, Celeste Rivas' Mom Breaks Down Over Possible Blood Evidence

Celeste Rivas' mom was doubled-over crying in court Thursday, TMZ has learned. But as witnesses took the stand, D4vd sat stone-faced.

During day 3 of the singer's preliminary hearing in Celeste's murder case, Samantha Tosch -- a criminalist with the LAPD Crime Lab's DNA Unit -- took the stand to discuss alleged DNA evidence.

Celeste's mom was crying and was handed a tissue during Samantha's testimony, as she was detailing possible blood samples that contained DNA profiles which were allegedly consistent with the young girl's.

Meanwhile, D4vd was sitting back in his chair with no reaction to the evidence being presented in court.

During her testimony, Samantha told Deputy District Attorney Beth Silverman that the DNA collected from red stains in D4vd's Tesla and garage were at incredibly high odds of being a match to Celeste.

She explained to the court that the potential blood found inside the car's trunk all indicated the DNA appears to be connected to Celeste.

When it came to the stain on the rubber floor mat in D4vd's garage, Samantha said that sample contained a partial profile consistent with Celeste's DNA profile.

She also said Celeste's DNA was excluded from the stained black trash bag at the scene ... but there were 4 alleged contributors, including D4vd and two other males.

As far as the disinfectant wipes inside the trash bag, she said that DNA is consistent with Celeste's -- 3 trillion times more likely to match hers -- and D4vd's DNA was excluded.