Floyd Mayweather -- Continues to Grieve ... In Courtside Lakers Seats

For the second night in a row, Floyd Mayweather decided to deal with the murder/suicide involving his friend Earl Hayes by sitting courtside at a NBA game.

Floyd -- along with model Liza Hernandez -- went to Staples Center and sat on the hardwood to watch the Lakers take on the Sacramento Kings ... laughing and smiling as if nothing was wrong.

Shocking ... considering Mayweather witnessed the horrific incident on FaceTime -- and you'd think a public place like a NBA game would be the last place he'd want to be.

As we previously reported, cops want to speak with Mayweather about the incident. We're told police have reached out to Floyd's people ... but they've been "less than willing" to cooperate.

Meanwhile, Kobe Bryant walked on to the court last night with a shirt that read "I Can't Breathe" ... as a tribute to Eric Garner.