BURTON, Mich. -- A Michigan mother killed during fighting in Syria often left many family members and friends in the dark about the details of another life -- marrying an Arab immigrant, moving around frequently and taking trips to the Middle East, including the one that would be her last, relatives said Friday.

An aunt, cousins, a longtime friend and the grandmother who raised Nicole Lynn Mansfield say they are left with differing, incomplete accounts of the life of the 33-year-old mother, who is the only American known to have been killed fighting in Syria. They say some of Mansfield's mysterious activity including a trip to the Middle East aroused the curiosity of the FBI, who contacted them a couple years ago to ask why Mansfield had travelled to Dubai for a few weeks.

"I was stunned, totally stunned, that she went over there and she got herself into what she got into and ended up away from us now," said Mansfield's aunt, Monica Mansfield-Speelman, of her niece's trip to Syria, where more than 70,000 people have been killed during two years of civil war.

Family members said FBI agents visited them Thursday and informed them of Mansfield's death. Simon Shaykhet, an FBI spokesman in Detroit, said he could confirm agents spoke to Mansfield's family, but he declined further comment. A pro-Syrian government news agency said Mansfield and two others were fighters for a group opposed to Syria's government and were killed in a confrontation in the northwestern city of Idlib. The report on the circumstances of the deaths could not immediately be confirmed.

Mansfield first became interested in the Middle East after a boyfriend introduced her to Islam several years ago, her relatives said. She continued with the religion after the relationship ended, going to services at a nearby mosque. She also started wearing a hijab and eventually did so around family despite their reservations.

She later married an Arab immigrant, got divorced and travelled to Dubai, telling her family at the time she wanted to learn more about Arab culture and the politics of the region, relatives said. Though family members asked questions, Mansfield, who has an 18-year-old daughter from a previous relationship, never told them the details of her marriage or trips overseas.

Mansfield-Speelman, who last saw her niece in August, said she and other family members did not approve of her niece's conversion from Christianity to Islam and her short-lived marriage to a man they never met. The aunt said she doesn't know the whereabouts of Mansfield's ex-husband.

Her grandmother, Carole Mansfield, said she remembered warning her granddaughter about the potential dangers of taking the Dubai trip alone.

"I said, 'Nikki, Nikki, Nikki, do you realize you're looking a rattlesnake in the face?"' Carole Mansfield said. "'Oh, Grandma,' I can still hear her say."

It was after that trip to Dubai that family said the FBI contacted them for information about Mansfield. Agents never told relatives why they were interested in her.

A law enforcement officer confirmed that Mansfield had been on the FBI's radar before she left for Syria. The official spoke on condition of anonymity because the official wasn't permitted to speak publicly about the investigation.

One of Mansfield's cousins, Deidra Mansfield, said she was close to her cousin for years growing up but they grew distant as she embraced her new faith and spent more time away from home. Diedra Mansfield said she and others unsuccessfully tried to keep her fully engaged with them.

"If I would call her, she'd act like everything was normal on the phone," she said.

She believed her cousin lived most recently in Detroit, where she told family she was attending a school. But she never provided any details about her education or her living situation.

One of Nicole Mansfield's close friends, Tasha Williams of Huntington, Ind., said she called in mid-May to say she would be returning on flight from Turkey to the U.S. in a few days after travelling to Syria to see man. She wanted to be picked at the Cincinnati airport.

"She said she was in a hotel room. She needed to get away from everything. I never heard from her again," Williams said.

Williams said she and Mansfield were certified nursing assistants.

"My boss was holding a position for her in Indiana. This is where she's supposed to be right now," Williams said.

The longtime friend was able to glean some details about Mansfield's other life that family members struggled to find out about. Williams said Mansfield met a man from the Middle East online and they married at the Grand Canyon in 2007 but divorced three years later when Mansfield learned he had another family.

Even if Mansfield got in over her head, Williams said she believed her friend would "absolutely not" take up arms.

"Nicole Mansfield has never been in a fight in her life except with me. We were 13 and became friends the next day. She's the biggest scaredy cat. ... She avoided drama at all costs," Williams said.

Carole Mansfield is less certain as she grieves her granddaughter's death.

"I don't think that we will ever be told the truth," she said.