We interviewed Allen Glover and many others for Monday night's 9 PM FOX primetime special, "TMZ Investigates: Tiger King -- What Really Went Down?" Glover made it clear ... he wished he could do more to hurt Joe as payback for, as Glover said, all the misery he caused people and animals. He even says he was gunning to pay Joe back.

As you probably know by now, Joe gave Glover $3k -- Glover says it was money to kill Joe's nemesis, Carole Baskin, but Joe says it was for him to get the hell out of the zoo.

Glover's testimony was critical, because he's the only person Joe actually gave money to, and that shows the overt act that the jury clearly felt proved Joe was out for blood.

But, what he told us -- that he wished he could do more to hurt Joe -- is the kind of bias that defense lawyers love, and juries look at with suspicion.

There's something else ... Jeff Lowe and others tell us about the number of people Joe spouted off to, saying he wanted to have Carole killed and even offered some as much as $50k to do the job. A lot of people felt those who are serious about murder for hire don't tell the world.

Tonight's special also gets into the new investigation into the death of Carole's second husband, Don Lewis. The Sheriff tells us he's suspicious of Carole and others, although he points out she's neither a suspect nor person of interest. Carole has denied any involvement in Don's disappearance.

And, we have exclusive information about various new federal investigations that are targeting people prominently featured in the series. We know the nature of the investigations, and why some federal agencies didn't give a damn until 'Tiger King' dropped.