Aaron Hernandez Back in Court -- BAIL DENIED

NFL star and murder suspect Aaron Hernandez has just been denied bail ... meaning he'll rot behind bars until his trial ... and that could take forever.

Hernandez was present in court today for a bail review hearing, where his lawyer begged the judge to release Hernandez from custody while he awaits trial.

But the judge wasn't moved by his arguments -- that Hernandez is an upstanding citizen and family man with no flight risk -- claiming the prosecution already had very strong evidence that Hernandez had committed the crime.

As for the evidence ... the prosecutor went through the entire timeline leading up to the murder of Odin Lloyd earlier this month, including matching shell casings found at the murder scene and inside Hernandez' rental car. He also mentioned the photo TMZ posted last night -- showing Hernandez brandishing a glock in the mirror 4 years ago -- claiming it's possible the murder weapon was also a glock.

The prosecutor said they'd be seeking the max sentence for Hernandez ... life without parole.

Hernandez' fiancee -- who was also present in court -- was inconsolable when the judge issued her decision to keep the NFL star behind bars.

As we reported, Hernandez was remanded into custody yesterday following his arraignment and was ordered to be held WITHOUT bail.

Hernandez has been charged with murder in the death of 27-year-old Odin Lloyd. He's also been hit with 5 gun-related charges.