An El Cajon man convicted of sex trafficking a 15-year-old girl in San Diego, Phoenix and Tucson was sentenced Friday to 10 years in prison, according to the U.S. Justice Department.
According to prosecutors, 21-year-old Samuel Melvin Cooper drove the teenage girl across state lines into Arizona for the purpose of performing sex acts. Text messages obtained by San Diego law enforcement officials revealed that he intended to leave the victim stranded if she did not give him enough money.
According to prosecutors, Cooper was arrested in September 2024 by San Diego police during a traffic stop in an area notorious for street-based prostitution. Authorities said he was using his phone to track two teenage girls, one of whom was a 15-year-old victim and the other an 18-year-old — a common practice among pimps.
Cooper pleaded guilty in October 2025 to one count of conspiracy to commit sex trafficking through force, fraud or coercion.
In his plea, Cooper also admitted that he sexually assaulted and prostituted another 15-year-old girl, despite having full knowledge of her age. Authorities recovered explicit videos and photographs of Cooper’s sexual conduct with the girl. According to the San Diego Human Trafficking Task Force, her birth year was the password for her phone.
“We will not allow the buying and selling of children,” said Adam Gordon, U.S. attorney for the Southern District of California. “This sentence reflects the deep harm that occurs when predators exploit minors for profit.”
Authorities said that after Cooper’s arrest, the first victim, a runaway, was crying loudly and denied any involvement in prostitution. Her mother said in a letter to the court that her daughter is still lost to her family.
“That letter speaks more powerfully about the lasting trauma of living on the streets and being in a situation at such a young age that your ability to be tied to commercial sex is more powerful than any lawyer can express in words,” the government’s sentencing memorandum said.
