Nearly six years after an Egyptian-born man allegedly gunned down his two teenage daughters in Texas, the manhunt for Yaser Abdel Said continues.

FBI officials say Said took his daughters Amina, 18, and Sarah, 17, for a ride in his taxi cab under the guise of taking them to get something to eat on Jan. 1, 2008. He instead took his daughters to a remote area in Irving, Texas, where he allegedly shot them multiple times. And although Said later fled his Dallas-area home with his Egyptian passport and $9,000, a private detective who has worked with the fugitive's sister-in-law told FoxNews.com he believes Said never made it out of the United States — and could even be behind the wheel of a yellow cab or livery car in New York City.

Said, who uses multiple aliases and is believed to be either 52 or 56 years old, is known to wear a thick mustache and dark sunglasses, including while indoors. He also prefers Denny's and IHOP restaurants and is known to carry a weapon with him at all times, according to Said's FBI wanted poster.

"A few days before she called me at my job and told me she was leaving because he had threatened the girls because they were dating."

- Connie Moggio, the girls' aunt

Said, of Sinai, Egypt, has passports from the United States and his country of birth. He also has ties to New York and Texas.

FBI officials in Dallas and New York told FoxNews.com that the hunt for Said is ongoing, declining further comment.

The New Year's Day double murder made national headlines in 2008 in part due to claims that the murders were an "honor killing," or the murder of a relative — typically a female — who is believed to have brought shame upon the family. In 2000, United Nations officials estimated that roughly 5,000 women worldwide were victimized in "honor killings," although most experts reportedly believe that figure is low.

Days after the murders, the older brother and aunt of the teenage victims told reporters that Said had a difficult time dealing with the beginning of his daughters' romantic lives. Connie Moggio, the girls' aunt, said her sister married Said at age 15 and tried leaving him several times, most recently just weeks before the alleged double murder.

"A few days before she called me at my job and told me she was leaving because he had threatened the girls because they were dating," Moggio told MyFoxDFW.com.

Brigitte Gabriel, author of "Because They Hate: A Survivor of Islamic Terror Warns America," said the killing had "honor killing written all over it," although the girls' brother, Islam Said, has denied that claim, saying Islam is a peaceful religion.

"The father was insulted and ashamed of how his daughters were behaving," Gabriel told FoxNews.com in 2008. " … The father probably was seeing that this is going to bring shame on the family and he needed to eliminate that shame."

Attempts to reach Islam Said and Moggio were unsuccessful. A police spokesman in Irving, Texas, told FoxNews.com that investigators believe Said killed his daughters because he was distraught over their romantic lives and their boyfriends, both of whom were white.

Meanwhile, the private investigator hired by Said's sister-in-law told FoxNews.com last year that Said likely never made it out of the Big Apple.

"It's all he knows, and I wouldn't be surprised one bit if he's there working as a taxi driver," Bill Warner told FoxNews.com. "He could blend in at a metropolis like New York."

Warner, who is based in Florida, said he believed the $9,000 Said took with him would not have been enough to establish a new life in a fresh location.

"He was not financially solvent," Warner said. "He did not own the cab he drove. He didn't have the financial strength to leave."

While New York's Taxi and Limousine Commission requires criminal background checks for anyone applying for a license, Said could have easily rented a licensed car via atypical means or merely use his own vehicle to pick up fares illegally, according to Fernando Mateo, president of the New York State Foundation of Taxi Drivers.

"There are 10,000 illegal drivers in New York City," Mateo told FoxNews.com last year. "It's as easy as getting in your car and driving to the airport or picking up illegal street hails."