Vincent Jackson likely died on or before Feb. 13 -- two days before he was discovered by law enforcement -- this according to a new death report obtained by TMZ Sports.
The former NFL star was pronounced dead on Feb. 15 after hotel staff contacted police about an unresponsive male in a room at the Homewood Suites in Brandon, Fla.
Cops had been investigating and now say hotel staff saw Jackson in the same room -- in the same slouched position -- as early as Feb. 13 ... but assumed he was sleeping.