Updated

A father accused of abandoning his 4-year-old son along a rural West Texas highway in the middle of the night was charged Thursday with attempted capital murder, prosecutors said.

Ann Reed, 32nd Judicial District Attorney, said she upgraded the charge against Carlos Rico after talking with the Sweetwater police chief.

"As the facts of the case developed it became apparent that the more serious charges were appropriate," Reed told The Associated Press.

The first-degree felony charge replaces the child endangerment charge he faced after another man found his son along Interstate 20 near Sweetwater about 3 a.m. Tuesday. The 22-year-old father is accused of choking the boy and dumping him on the road about three hours before he was found.

Rico remained in the Nolan County jail on Thursday with bail set at $500,000. Jail officials said they did not know if Rico had an attorney and referred inquiries to the justice of the peace, who did not immediately respond to a phone message seeking comment.

Police say the boy was picked up by a local high school basketball coach and taken to a hospital, where doctors removed at least 500 cactus spines from his body. He was released from the hospital Wednesday and has been placed into foster care.

Rico was driving from Lubbock to Saginaw when he abandoned his son, and he was taken into custody Tuesday by police in the Fort Worth suburb, Saginaw police spokesman Damon Ing told The Associated Press on Wednesday. Rico's cousin called police when Rico showed up to see him without his son, and investigators determined that Rico was the boy's father, he said.

Al Hunt, the Sweetwater High coach who found the boy, said he initially thought he was looking at a guardrail post until it moved.

"It took me seconds to realize, 'it's a little kid there,'" the 54-year-old said.

He said he pulled over and, not seeing a vehicle that the child might have been in, ran across the road and scooped the boy into his arms. He said the boy's lips were cracked as if he were dehydrated, and that the only response the boy was able to give to his questions was to hold up four fingers when Hunt asked his age.

The boy's stepmother in Lubbock came to Sweetwater to be with him. The whereabouts of the boy's biological mother were not immediately known, and it was unclear if she is involved in his life.

Sweetwater is about 125 miles southeast of Lubbock.