Matthew McMahon, who advocated for his daughter and her half-siblings following the murder of their mother, Rachel Morin, has been charged with possessing child sexual abuse materials.

McMahon, 51, was arrested at his Bel Air home Tuesday on 10 counts related to possession of photos and videos depicting child sexual abuse, according to a Maryland State Police news release.

A state trooper assigned to the Harford County Child Advocacy Center began investigating McMahon in September, according to the news release.

Court records do not list an attorney for McMahon.

McMahon is the father of Rachel Morin’s eldest daughter, Faye, who was the executor of her mother’s estate. He spoke frequently with the media about the impact of Morin’s murder on his daughter and her four younger siblings.

Morin, 37, was raped and murdered on Aug. 5, 2023, while jogging on the Ma & Pa Heritage Trail near her Bel Air home.

The case quickly drew national attention, which intensified in the following year when Victor Martinez-Hernandez, a native of El Salvador who was in this country illegally, was arrested for her murder. President Donald Trump spoke about the case on the campaign trail and invited Morin’s relatives to join him in public appearances.

In August, Martinez-Hernandez was sentenced to life without parole for his convictions on first-degree murder, rape and other offenses.

The following month, Morin’s children reached a confidential settlement with their grandmother and aunt. The children had sued Morin’s mother and sister, saying they had not received proceeds from fundraisers.

McMahon was being held without bail at the Harford County Detention Center, according to the news release.