Ex-Notre Dame RB George Atkinson III -- son of former Super Bowl champ George Atkinson II -- died on Monday ... less than 1 year after his twin brother committed suicide.
It's unclear how the 27-year-old passed ... but the former NFL player said losing his brother, Josh, last December took a serious toll on him.
In a letter penned by Atkinson III in October ... he said Josh's death put him "on an emotional roller coaster and in a real dark place."
Atkinson III admitted he attempted to "harm himself" shortly after the death and had to be institutionalized ... but said his 2-year-old daughter was keeping him going.
"Without my daughter," Atkinson III wrote, "I don’t know where I would be right now. She gave me that second wind of motivation."
Atkinson III was a top recruit in the country coming out of high school in 2011 ... and was a stud for Notre Dame from '11 to '13 -- scoring 10 career TDs.
He went on to play two seasons in the NFL, one for the Raiders and one for the Browns ... and scored a memorable preseason TD in 2016.
These @Raiders can flat out fly!
— NFL (@NFL) August 13, 2016
George Atkinson is takes this one 53 yards to the HOUSE. #OAKvsAZ https://t.co/YskT7uR7Yz
Atkinson III's father was a star returner and defensive back for the Raiders, making two Pro Bowls and helping Oakland win Super Bowl XI over the Minnesota Vikings.
RIP
If you or someone you know is suffering from depression, please get help. Here's a link to the National Suicide Prevention Lifeline.