Julia Crabbe's family wants to know why Montae Nicholson did NOT call 911 when she was dying of a drug overdose -- and they went to FedEx Field on Sunday to get answers.
TMZ Sports broke the story ... cops say Nicholson dropped Crabbe off at a Virginia hospital on Nov. 13 and left the scene, despite the fact she appeared dead on arrival.
Officials have NOT accused Nicholson of any criminal wrongdoing, but Crabbe's family is clearly PISSED at the NFL player ... and they want answers.
"In her time of need, no one decided to call 911," Crabbe's aunt, Shirley Kirkland, told FOX 5 in D.C. ... "If they just would've called 911, she may have had a chance at life."
Several members of the family wore shirts with messages directed at Crabbe including -- "#JusticeForJulia" and "#35NeverCalled911."
Of course, #35 is Nicholson's jersey number.
As for the investigation, officials believe 21-year-old Crabbe had been at Nicholson's home in the hours before she died.
Cops obtained a search warrant and found several concerning items at Nicholson's home including marijuana, prescription pills and foil with residue.
Crabbe's father told FOX 5 his daughter had been dating Nicholson for several months before she died ... and he's upset Nicholson hasn't contacted the family since her passing.
For his part, Nicholson says he's cooperating with police and says the days since Julia's death have been "extremely hard" on him.