A murder charge was dropped Friday against a man who had been accused of fatally stabbing an 11-year-old Houston boy as the child walked home from school because the man's alibi checked out, authorities said Friday.

Houston Homicide Lt. Robert Blain said that means the person who did kill Josue Flores on Tuesday afternoon "is still loose at this point," and provided a description of a possible suspect. Residents in the neighborhood where Josue was stabbed said Friday they're upset and scared that the killer is at large.

Detectives found physical evidence to support the contention of Che Calhoun, 31, that he was in a suburb south of Houston when Josue was killed.

"As our common practice, we began working to see if we could confirm or disprove his alibi," Blain said. "We wound up locating several witnesses from his alibi, interviewing them, and late last night wound up recovering physical evidence and showed he was down in Pearland and could not have been at the location where the murder occurred."

Calhoun, who has an extensive criminal record, remains held on charges of assault and evading arrest in connection with a confrontation with a transit officer on Monday. Blain said Calhoun has acknowledged involvement in that incident.

On Tuesday, several witnesses told officers they heard loud screaming and saw Josue, a sixth-grader who was walking home from a science club meeting at Marshall Middle School just north of downtown Houston, struggling with a man. The boy collapsed on the grass near the sidewalk and the man ran off. A bystander flagged down police and alerted them to the wounded boy, who was taken to a hospital with multiple stab wounds and pronounced dead a short time later.

Court documents showed three people described Calhoun as the man seen fleeing from the scene. Police obtained an arrest warrant and federal marshals arrested Calhoun on Wednesday. Blain said his detectives "don't rely solely on eyewitness identification," noting that Calhoun was identified by a witness presented with a photo lineup.

Omar Garza, 18, told The Associated Press on Friday that he was the person who identified Calhoun in the photo lineup and that he still believes he identified the right person. His mother, Patricia Garza, 39, said Josue's killing was a sad example of crimes, such as robberies and drug dealing, that have steadily increased in the neighborhood where she's lived her entire life.

"Since this happened, I'm really scared now," she said, saying she was concerned for her son's safety and feared possible retaliation against him.

As they did earlier in the week, police said Friday that the suspect they're now looking for is a black man who is about 180 to 220 pounds and 6 feet tall, who wore a black shirt and black pants and had a green jacket draped over his shoulder. Blain said police believe because of the nature of the attack, he likely had blood on him.

"This was a horrendous crime," Acting Police Chief Martha Montalvo said. "We're going to do our due diligence. ... We're not going to stop. We're going to do what we need to do to resolve this."

More than a dozen residents gathered Friday afternoon at the site where Josue collapsed and where a growing memorial of balloons, candles and stuffed animals sits under a tent. Motorists dropped cash in containers to help his family with expenses for his funeral, set for Tuesday.

Many said they were upset and scared to learn his killer remained at large.

"I don't feel safe right now," said Maria Tenorio, 48, who has three sons. "As a mother, this hurt me that this happened."

Tenorio said she believed someone saw the killer and implored them to call police.

Patricia Cerna, 52, who lives next door to where the boy was attacked, said she heard his cries and saw the assailant run from the scene but wasn't able to see his face. A neighbor chased the attacker in his car but lost him after the man crossed some railroad tracks, she said.

Meanwhile, Cerna rushed outside to the wounded boy.

"Look at what happened to this little angel, this little boy," she said, crying as she recalled the scene.