A dead man was found under a mattress in a Midtown hotel early Monday morning. 

Officers responded to the Hilton Garden Inn at 63 W. 35th St. around 4:10 a.m. on Monday, and found the man under a mattress with trauma to the back of his head. 

The victim, who has not been identified, was pronounced dead at Bellevue Hospital. The investigation continues, and the medical examiner will determine the cause of death.