Authorities say the 15-year-old girl was hit by a stray bullet during a shootout Sunday in Lexington, Kentucky.
Lamonte A. Williams, 20, was charged with wanton endangerment in the killing, police said Wednesday. On Thursday, he entered a not-guilty plea to the charge.
Lexington police have already charged Chazerae Taylor, 38; D'markeo Taylor, 19; and Dvonta Middlebrooks, 21, with wanton endangerment in the girl's death.
Investigators believe the four fired multiple shots in the parking lot of a Cook Out restaurant, where Trinity Gay was struck in the neck, according to a Lexington police statement.
Police have recovered a blue Ford that matches witness descriptions of one of the cars that fled the scene following the shootout, and a gray Dodge Charger used in the shootout, according to the police statement.
Police said the investigation "remains active and is still in the early stages." Investigators working in conjunction with the Kentucky State Police crime lab are gathering forensic, digital, testimonial and other evidence.
'I'm so confused'
The shooting erupted around 4 a.m. Sunday when men in two cars opened fire on each other in the restaurant parking lot, police said. Trinity Gay was not a passenger in either vehicle, they said.
The girl was taken to the University of Kentucky Hospital in a private vehicle, where she later died, police said. The Fayette County coroner confirmed she was the track star's daughter.
Tyson Gay told CNN affiliate WLEX-TV
that he had few details about his daughter's death.
"She didn't make it. I'm so confused," the former world 100- and 200-meter champ told the station. "She was just here last week for fall break. It's so crazy. I have no idea what happened."
He flew from his home in Orlando to Lexington on Sunday.
Like father, like daughter
A Lexington native, Gay is the second-fastest man
to run the 100-meter sprint, behind Usain Bolt. He ran the 100 meter in 9.69 seconds in 2009, matching Bolt's gold-winning effort at the Beijing Olympics in 2008. (Bolt ran a 9.58 at the 2009 World Championships in Berlin.)
Gay won gold medals in the 100-meter, 200-meter and 4x100-meter relay at the 2007 world championships in Osaka, Japan. He had to return a silver medal he won for his part in the 4x100-meter relay at the 2012 London Games after testing positive for steroids. He also served a one-year ban from his sport.
Trinity Gay was a rising track star herself, a sprinter for Lafayette High School in Lexington, according to CNN affiliate WKYT-TV
"I'm at a point where I want to be involved in more of her sports," he said. "It was pretty amazing to watch her run and compete and still keep her spirits up high when she didn't win."
'Our hearts are broken'
Condolences poured in from friends and associates of both father and daughter.
"Please join us in keeping the Gay family close in thought and prayer and supporting the students, staff and families at Lafayette High during this unspeakably difficult time," Fayette County Schools Superintendent Manny Caulk said in a statement.
The school system has activated a crisis team to offer counseling and support to students and staff.
Local schools and track teams expressed their grief, too.
Athletes and Olympians offered condolences on social media. Jamaican sprinter Asafa Powell wrote, "Bro want to send my condolences ... can't even imagine what you must be going thru."
Fellow U.S. Olympian Lolo Jones wrote, "Heavy heart today for Tyson Gay and his family. Lord please ease their pain and give them strength during this time."