Documents from a 2008 child custody battle in San Diego between Esteban and former boyfriend Scott Marasigan reveal a pattern of erratic behavior on the part of Esteban.
Marasigan wrote to the court, "Giselle has exhibited sometimes manic moods which have led to the escalation of the arguments to violence."
Esteban, 27, is one of nearly three dozen people Hayward police have identified as "persons of interest" in the disappearance of nursing student Michelle Le. Le disappeared on May 27 from the parking garage of Kaiser Hospital in Hayward.
In a call to ABC7, Esteban claimed she "hates" Le because of Le's friendship with Marasigan, but Esteban told us she had nothing to do with Le's disappearance.
"We did not in any way ask her to contact Channel 7, she did that on her own," Hayward Police Sgt. Steve Brown said. "So commenting on Giselle or anybody else we've talked with at this point would be premature, speculative and would just add to the complexity of the investigation."
ABC7 has also confirmed three days before Le disappeared, Marasigan was granted a restraining order against Esteban for bizarre behavior that included stalking his home. He feared she had a gun.
On Monday, police searched Esteban's Union City condo for the second time in connection with Le's disappearance.
Another former boyfriend in San Diego says Esteban has a short temper.
"She had a very, very short temper and when she flies off the handle, she really flies off the handle," Cole Gabaldon said.
Meanwhile, despite police statements she was likely murdered, Le's family is still hopeful she is still alive.
"We're still printing t-shirts, printing flyers; we still have reason to believe she's alive, we still have the hope," Le's cousin Krystine Dinh said.
Le's family is planning a vigil for Thursday at 7:30 p.m. at Mount Eden Park in Hayward.
As for Esteban, police say they know where she is and she has been cooperative.