Football coach, 46, is shot dead in his home with his own handgun by his ...

A 15-year-old boy confessed to fatally shooting his cousin, a beloved Miami high school football coach, while staying over his house and robbing him of $7,000 in cash, police said.

Charles Alexander, who is said to have a history of mental illness, has been charged with second-degree murder and armed grand theft in the killing of 46-year-old Corey Smith on Monday.

Prosecutors in Miami-Dade County plan to charge him as an adult, the Miami Herald reported.

Alexander was staying at Smith’s home in West Little River when he used the football coach’s own 9mm Beretta handgun and shot Smith dead in a den, according to police.

Corey Smith, 46

Charles Alexander

Corey Smith (left), 46, the head football coach at Miami Senior High School, was shot and killed by a close relative, Charles Alexander, 15, in his home in West Little River, Florida, on Monday, according to police. Alexander is seen right during an appearance in Miami-Dade juvenile court on Friday

Alexander, who is said to have a history of mental illness, will be tried as an adult by prosecutors in Miami-Dade County, it has been reported. He was arrested on Thursday after his mother called police and told investigators that he confessed to the shooting

Alexander, who is said to have a history of mental illness, will be tried as an adult by prosecutors in Miami-Dade County, it has been reported. He was arrested on Thursday after his mother called police and told investigators that he confessed to the shooting

Surveillance footage showed that Alexander was the only person at home at the time of the shooting, it is alleged. Police also said Alexander confessed to the shooting to his mother.

Investigators also found more than $7,000 in cash belonging to the coach inside a pair of jeans hidden in Alexander’s black bag, police said.

During a hearing in Miami-Dade juvenile court on Thursday, a judge ordered Alexander be held in secure detention.

Charles Alexander is the son of 41-year-old Lamar Alexander, the convicted felon who was shot and killed after carjacking a UPS truck and leading police on a high-speed chase last November.

Police responded to the scene on Monday after gunshots were heard coming from Smith's home in West Little River

Police responded to the scene on Monday after gunshots were heard coming from Smith's home in West Little River

According to investigators, Alexander shot Smith with the coach's own 9MM Beretta gun (like the one seen in the above file photo)

According to investigators, Alexander shot Smith with the coach's own 9MM Beretta gun (like the one seen in the above file photo)

Alexander and another ex-con who took part in the armed robbery, Ronnie Jerome Hill, 41, were killed.

The UPS driver they took hostage, Frank Ordonez, 27, and another motorist who happened to be in the area, Richard Cutshaw, 70, were also killed.

The entire incident was caught on television.

Corey Smith and Lamar Alexander were technically cousins, but they were so close growing up that they were seen as brothers.

Alexander’s son, Charles, was thus considered Smith’s nephew.

Smith’s loss is a blow to the community, which knew him as the head coach of the Miami Senior High School football team.

‘In life, you gotta make better decisions,’ Smith said of Lamar Alexander the day after the hostage shootout.

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