In court Thursday, James Berry appeared in his robe to hear the charges against him.
According to police, computer repair shop employees discovered images of naked children on Berry's computer.
"It was impacting, disgusting. You know something is wrong. You have to let someone know," Friendly Computers operations manager Antonio Rodriguez said.
The employees inside the store contacted law enforcement.
TIMELINE: 77-year-old charged with sexual assault
"I just wanted this guy to go directly to the jail," IT specialist Rafael Vera said.
During the investigation, Berry's home was searched and he admitted to having sexual contact and recording the crime on his iPhone. Police believe the alleged sexual assault happened in January 2016.
Investigators say the girl initially contacted Houston police on March 22.
The case hadn't been assigned to an investigator by June 13 when Webster Police Department received the tip.
In a statement to ABC13, HPD says the case was not assigned because the girl was out-of-state and not living with the suspect.
If she was in the area, the case would have been moved up in priority.
Berry was arrested and taken to the Harris County jail Wednesday. Bond was set for $275,000.