Bobbi Kristina Death Investigators Interview Nick Gordon's Girlfriend

Nick Gordon's domestic violence arrest got the authorities investigating Bobbi Kristina Brown's death to board a plane and go talk to the girlfriend he allegedly beat up.

Fulton County Assistant D.A. Seleta Griffin landed back in Atlanta Thursday and told reporters the alleged victim "had a lot to say." She added ... the interview moved them closer to finding out the truth about the circumstances surrounding BK's death.

TMZ broke the story ... Nick's facing domestic violence battery and kidnapping/false imprisonment charges. He's accused of beating up his girlfriend in a jealous rage.

Remember, Nick was found legally responsible for Bobbi Kristina's death. The criminal investigation remains open after 2 years, and Nick continues to be a person of interest.