A man being questioned by Turkish authorities in the murder of a New York tourist found beaten to death in Istanbul has reportedly told authorities there he had a sexual relationship with the woman.
The Turkish man, identified only as "Taylan," gave DNA and sperm samples to police investigating the death of 33-year-old Sarai Sierra, a mother of two found beaten beyond recognition near ancient walls in Istanbul, the Turkish daily Vatan reported Wednesday. The man told investigators he had a consensual sexual relationship with Sierra before she was last seen on Jan. 21, according to the newspaper.
But Sierra's best friend, Magdalena Rodriguez, told FoxNews.com she doesn't believe the man's claim.
"We know Sarai. We know she didn't run off with anybody," said Rodriguez, who originally planned to accompany Sierra on her solo vacation to Istanbul.
"She would have told me. She would have said something," said Rodriguez, who claims she was in constant contact with Sierra during the trip.
"I don't believe what he [Taylan] says for one second," she said, adding, "Sarai wouldn't willingly and knowingly involve herself with people who did not have her best interest at heart."
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Sierra, a freelance photographer from Staten Island, N.Y., traveled to Istanbul Jan. 7 and failed to return on a flight Jan. 21.
Turkish authorities say Sierra died from a single blow to the head. A local funeral company on Tuesday told the Hürriyet Daily News, an English-language newspaper in Turkey, that she had multiple injuries to her head and face.Her body was found Saturday near remnants of the city's ancient walls. Turkish police said there appeared to be no sign of a sexual assault, though the New York Daily News reported the woman was found in only a shirt and underwear. Sierra's gold jewelry was still on her, but her tablet computer and U.S. cellphone are missing.
A source familiar with the investigation told FoxNews.com that Sierra had contacted "amateur tour guides" online in advance of her trip. Taylan was among the individuals whom she had communicated with, and the two were known to have met on Jan. 13, according to multiple Turkish media accounts. The pair had planned to meet by the Galata Tower on Jan. 21 -- the day she was last seen -- but Taylan reportedly told investigators that Sierra never showed up.
Rodriguez claims she and the family were aware of Sierra's online communications. "We knew about the tour guides ... We knew she planned to meet them," she said, adding, "She's not one to just meet a random person and then wander away with them."
New York Rep. Michael Grimm, a former FBI agent, said Turkish police still have hours of video footage to review as they piece together Sierra's last movements. A special unit of Turkish police set up to find Sierra has an image of her at Galata Bridge, which spans Istanbul's Golden Horn waterway and where she went on her last day to take photos. An FBI official confirmed to FoxNews.com that the agency is also involved and has been since the early stages of the investigation.
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During her trip, Sierra made two pre-planned excursions to Munich and Amsterdam, and then returned to Istanbul. Authorities are probing Sierra's trips to Munich and Amsterdam as part of the investigation into her death. Friends and family insist Sierra visited the three places because she was "in love" with the architecture and culture of those cities and wanted to practice her photography.
"We knew she was going to Munich and Amsterdam. Nothing about this trip was a surprise. She made her own route and that's what she wanted to do," Rodriguez said.
Prosecutors in Istanbul got a court order Monday for authorities to take blood and DNA samples from 21 people already questioned in the death, according to Turkish state media.
Samples reportedly taken from under Sierra's fingernails suggest she may have tried to fight off her attacker. A blanket was also found near the body, leading investigators to question whether she was killed in another location and then placed near the ancient walls, which are close to a highway.
Sierra's husband, Steven, is still in Istanbul, where he traveled last week to help in the search. The woman's body is reportedly being flown out of the country for free on Thursday by Turkish Airlines. Sierra's family sold many of the her photographs online to help pay for her funeral. Any additional funds will go to Sierra's two young sons, who have not yet been informed of their mother's death.
FoxNews.com's Cristina Corbin and the Associated Press contributed to this report.