Katherine Jackson -- 'Justice Has Finally Been Served'

Katherine and Joe Jackson are "ecstatic" about the guilty verdict in the Conrad Murray manslaughter case ... telling TMZ, "Justice has finally been served."

MJ's parents just released a statement ... saying, "We have been waiting for this moment for a very long time and we couldn’t hold back tears of joy in the courtroom. Even though nothing can bring back our son, justice has finally been served!"

The two added, "We can’t wait to go home and share this day with Michael’s children.”