A possible auto-pedestrian hit-and-run turned into a homicide investigation after an autopsy report revealed the victim had been shot prior to being run over, according to an arrest affidavit.

Gustavo Sandoval Linan, 28, is accused of committing murder in the first-degree on Sunday, Aug. 20.

Police said they responded to the Idlewild Apartments located in the 8930 block of Galewood Drive, near Rundberg Lane and Metric Boulevard, at 3:18 a.m.

There, officers said they found Austin-Travis County Emergency Medical Services tending to the victim, identified in the affidavit as Valente Garcia Hernandez, 35, who was reportedly lying on the ground with a pool of blood around his head and tread marks on his black pants.

Hernandez was pronounced dead at 3:31 a.m.

Detectives at the scene made contact with Hernandez's girlfriend, who informed officials that they had just returned home from a family party and were unloading their vehicles when she heard a "pop". The girlfriend's 9-year-old son told police he saw a man wearing a baseball cap drive off fast from the apartment complex after he heard what sounded like a "firework", the affidavit said.

Another witness at the scene said he saw Hernandez taking trash to the dumpster and stopping to talk with his girlfriend while she was still seated in her car. The witness said following the exchange he saw Hernandez walk to the side of a green or gray Chevrolet Tahoe that had driven in behind his girlfriend, and watched Hernandez throw a bag of trash towards the driver side of the vehicle. The witness told detectives he then heard a "pop" and saw Hernandez fall to the ground.

A second witness said he saw the same exchange but also allegedly witnessed the driver aim a handgun out of his window to shoot Hernandez. When the driver was attempting to exit out of the complex, he ran over Hernandez to exit out of the proper entrance, the witness said.

On Aug. 21, the Travis County Medical Examiner's Office completed the autopsy report for Hernandez and dislodged a "fully jacketed projectile" from the back of his head. The affidavit said he died as the result of a gunshot wound.

Through further investigation, detectives spoke with Hernandez's girlfriend again and found out that she and Hernandez were in the process of separating, and were dating new people. One of the people she told police she was dating was Linan. The girlfriend told officials Linan had informed her that they wouldn't date until she was fully separated from Hernandez. The girlfriend said Linan drives a Chevrolet Tahoe, the same vehicle described by another witness, and carried a small handgun inside his vehicle.

A day after the autopsy report was completed, the girlfriend told police that her son saw Linan exit the parking lot of the apartment complex after the shooting incident.

Investigators said they discovered Linan resides at the Autumn Chase Apartments, which is four tenths of a mile from the Idlewild Apartments. After gaining access to the complex's security cameras, the affidavit said investigators saw the Tahoe exit the complex at 3:14 a.m. The original incident report at the Idlewild Apartments was reported four minutes later.

Travis County jail records do not show if Gustavo has been taken into custody, as of 1 p.m. Wednesday, Aug.23.