An Upper Darby man was charged with first-degree murder on Friday after he confessed to police that he killed his ex-wife and abandoned her body on the Schuylkill River Trail in Valley Forge National Historical Park, authorities said.

Freddy Remigio Mendieta Pando, 23, surrendered to police in Upper Darby on Thursday morning. Mendieta Pando, who authorities say does not speak English, walked into the police station and used a translation app on his smartphone to tell the officers “I killed my partner,” according to the affidavit of probable cause for his arrest.

He remained in custody Friday, denied bail. There was no indication he had hired an attorney.

Mendieta Pando told police he stabbed Karina Torres, 23, to death on the trail in Lower Providence Township on Sept. 11 during a meeting they had arranged to discuss an ongoing domestic violence case, the affidavit said. He had been arrested in July and charged with simple assault, harassment, and terroristic threats for allegedly punching, strangling, and threatening to kill Torres during an argument at their apartment in Upper Darby, according to court records.

Mendieta Pando was released on bail in that case but barred from contacting Torres under the terms of a temporary protection-from-abuse order she had obtained against him, court records show.

During his interview with detectives Thursday, Mendieta Pando admitted that he stabbed Torres multiple times in the chest and later discarded the knife by throwing it into the river, the affidavit said. He said he hid her body under some trees, but marked its location on a map, indicating that it was near the Betzwood Trailhead inside Valley Forge.

Montgomery County detectives later found Torres’ body in that location.

Mendieta Pando said the couple met in the park and got into an argument, and Torres pulled out a knife, according to the affidavit. He told police he wrested the knife away from her and stabbed her multiple times, covering her mouth to prevent her from screaming, the affidavit said.

Montgomery County District Attorney Kevin Steele said Torres’ death was “the worst end result of domestic violence.”

“People who are strangled by a spouse or intimate partner need to know that they are in serious danger — they are likely to be killed by that person, as in this terrible case,” Steele said. “Women experiencing domestic violence need to know there is help available.”