Indiana mother Amber Pasztor was arrested Monday on two preliminary counts of murder after allegedly abducting and killing her two children. An Amber Alert was issued for the two children Monday morning that said Liliana Hernandez, 7, and Rene Pasztor, 6, were “believed to be in extreme danger,” the Associated Press reported.

Hours later, the two children were discovered dead in a car parked outside of a police station in Elkhart, after Pasztor allegedly approached an officer outside of the station. A coroner confirmed that both children had perished from asphyxiation, CBS News reported.

Amber Pasztor has a checkered past with her children. Pasztor, 29, who has an alleged history of substance abuse, threatened before to harm both of her children. Following the threats, the two children were taken out of their mother’s custody nearly two years ago, family members said. Both Liliana and Rene went to live with Pasztor’s step-grandmother, Emily Lasko Green, People Magazine reported Monday evening.

“We fought so hard for [Rene and Lilian]. We walked through hell to get them,” Green told People.

Amber Pasztor’s father said his daughter had battled drug addiction, according to WSBT. He had custody of both children for a little over one year.

Pasztor’s mother, Leanne Pasztor, described her daughter as “evil.” “We thought she was crazy,” Leanne Pasztor told People. “I think her thought was, if she can’t have them, nobody can.”

Elkhart is around 70 miles northwest of Fort Wayne, which is where the children were living with Green. Elkhart police Sgt. Chris Snyder told CBS News that Pasztor parked a car Monday outside the Elkhart police station and started chatting with a police officer.

“She pulled up to him and explained to him that she was part of the Amber Alert and the two kids were in the back seat,” Snyder told the news outlet.

The two deceased children were discovered within the car. The vehicle belonged to Pasztor's neighbor, Frank Macomber, who was 66, according to CBS News. His body was discovered by police in a wooded area near his home following Pasztor's arrest. The outlet reported that Macomber had likely been killed prior to the children's abduction. His death was ruled a homicide, according to ABC News. Macomber and Pasztor were reportedly believed to have been together on Monday.

Police said Pasztor was cooperating with police and became emotional at one point following her arrest. She faces two preliminary counts of murder and was being held in Elkhart County jail.