WHITTIER, CA—On Friday, Sept. 11, 2015, Hun Joon “Paul” Lee was found deceased in a school bus at approximately 4:25 p.m. Whittier Daily News reported that Lee may have been left in the bus for several hours.

Lee, 19 years old, had autism, and his mother Eun Ha Lee claimed that her son had the mind capacity of a 3 year old. Additionally, Lee was incapable of speaking rendering him unable to communicate for someone to help him.

Before the tragedy, Lee’s mother sent him to his bus at the normal time around 8:30 a.m. On the bus, there were only two other students other than Paul to reach their destination at Sierra Vista Adult School. At the end of the school day, Lee was confused because her son had not returned home. Lee decided to call the bus company, but after receiving no response, she contacted one of Paul’s teachers. The teacher reported that Paul had never attended class that day. Immediately after hearing this, Paul’s mother notified the police and traveled to the school.

Once the police arrived, they began looking for Paul and found him deceased on the bus. The cause of death is still unknown even after an autopsy was performed. While Paul was on the bus, there were temperatures that reached over 100 degrees that day which could have caused a heat stroke.

According to the family, Paul was the center of their family, and they are still trying to cope after their loss. “I feel like we are nothing,” Mrs. Lee said. “They killed my son.”

This has been one of eight cases in three years which include an autistic kid being left alone on a bus.

On Tuesday, Sept. 22 a candle vigil was held for Paul on what would have been his twentieth birthday.

EDIT: On March 23, bus driver Armando Able Ramirez was arrested for dependent abuse in Paul’s death.