An 18-year-old murder suspect with ties to Phoenix has been added to the FBI's "Ten Most Wanted Fugitives" list, the FBI said Tuesday.

The FBI is offering a reward of $100,000 for information leading directly to the arrest of Alejandro "Alex" Castillo who investigators allege is responsible for murdering a 23-year-old woman in Charlotte, North Carolina in 2016.

Truc Quan "Sandy" Ly Le's body was found on Aug. 17, 2016 in wooded area just outside of Charlotte with a gunshot wound to the head. Two days prior, her car was located in Phoenix. Investigators have uncovered video surveillance of Castillo crossing the border into Mexico from Nogales, Arizona on Aug. 16, 2016.

Ly Le and Castillo worked together at a restaurant, and the FBI said they were romantically involved. Charlotte police determined Ly Le lent money to Castillo, and Castillo texted her on Aug. 9, 2016 saying he wanted to meet up with her to pay her back.

Shortly after, Ly Le, Castillo and a third coworker Ahmia "Mia" Feaster were reported missing, according to the investigation. Feaster crossed the U.S.-Mexico border with Castillo and later turned herself in.

Castillo's last known residence was in Charlotte, but he has family ties in Phoenix, the FBI said. Investigators believe he is armed and dangerous and may be in the Mexican states of Aguascalientes, Guanajuato or Veracruz.

Castillo was born in Arizona. Investigators describe him as 5'6" tall, 180 pounds, with short black hair and brown eyes.

Anyone with information on Castillo’s whereabouts should call the FBI at 1-800-CALL-FBI. Tips can also be submitted online.