It’s not clear that the graffiti was left at the same time as the hanging. I’m not a suicide expert but “RIP Randy Leo Dudley, too good 4 this world” is not what I’d call a suicide note. My guess is a friend of theirs came later and left it to pay respects. The article mentions “Two of Dudley’s housemates said that he was found … near the mini-park’s slides,” so they knew where Dudley was found.

That said, I’m not convinced this was a lynching. I agree with his sister:

Chanell Dudley said the office had shared details about the manner of Dudley’s death, and that she was inclined to believe the preliminary ruling. She said she is still awaiting a full investigation from the medical examiner, however, and was hoping for “all the facts.”