Was U.S. aid worker in Afghanistan killed for her newfound Christian faith?

As U.S. aid worker Lisa Akbari left the gym at her apartment complex Sunday night in Kabul, Afghanistan, someone fatally shot her.

A few miles from the attack, Afghan police arrested a mullah, or Muslim scholar, who lives at the same complex, authorities said. He was injured during the arrest and had to be hospitalized. As of Monday, he had not been questioned.

But investigators found documents in the mullah’s apartment linking him to terrorist groups, according to Kabul District Police Chief Fraidoon Obaidi.

Akbari, a 25-year-old American, lived in Afghanistan for three years. Mayana Aliah Akbari told CNN her sister recently become a Christian and had been making efforts to share her faith.

“We’re not sure if that’s the exact reason for her death,” Mayana said. “She wanted to spread the word. I guess she said the words to the wrong person.”

Akbari moved to Afghanistan in part to learn about her heritage. Her mother is from Iran and her father from Afghanistan.

“She was always wanting to learn more about Dad’s culture,” Mayana told CNN. She also “wanted to help women and children … have more education and rights.”

Akbari’s friend, Tahirah Spears, told me Akbari loved working in Afghanistan.

“She really wanted to make a difference in the lives of people who were not allotted the freedom we have here in the United States,” Spears said. If Akbari could make a difference to someone else, “she went for it without even caring about her own safety.”

According to Akbari’s LinkedIn profile, she worked most recently for the Colombo Plan, a foreign aid organization based in Sri Lanka. The organization has a program in Afghanistan, and Akbari wrote that she worked on a women’s shelter capacity assessment throughout the country.

For four years, Akbari worked for the U.S. Army as a research manager for the Karadah Project International.

“Her contributions to our mission were both critical and essential to our success,” project founder Rick Burns commented on LinkedIn.

In September 2012 and December 2014, Akbari worked as a contracted consultant for the Christian relief organization World Vision in Badghis, Herat, and Ghor provinces, evaluating the organization’s Food for Education project in western Afghanistan.

Jim Alexander, World Vision's Afghanistan national director, wrote in a statement that the organization “lost a valued colleague” and sympathized with Akbari’s family.

“Our prayers go out to them and to her friends who must be so deeply shocked and grieving during this time,” Alexander said.

The family’s loss “feels like a living nightmare,” Mayana Akbari wrote on Facebook.

“I know God got back his angel and is proud of you for all that you’ve done on earth while you were still living,” she said in a post Sunday night.