After events in Episode 1, Jedi (and mostly everyone else) assumed Darth Maul to be dead. Yet, he reappears and challenges Obi-Wan who gets beaten pretty badly.
Considering the importance of Maul (he was after all One of Two, he definitely knew Darth Sidious' identity, and presumably other Sith secrets), and his combat capability, why didn't the Jedi send some more experienced and powerful masters or knights after him (Yoda, Windu, Anakin, Fisto, or even better, all of them). Instead, they leisurely let him rampage, with Kenobi as only Jedi confronting him (although Kenobi considers himself and Ventress as outmatched against Maul and Savage Opress). The only so called help Obi-Wan gets from other Jedi is weak Jedi Master Adi Gallia - she gets killed relatively easy by Savage Opress and Savage is shown to be no match for Maul.
Later Palpatine himself gets down to business, cutting lose ends, but it seems completely counter-intuitive even for arrogant and not-so-smart Jedi to just let this opportunity slip away. I'm pretty certain Yoda and Windu could disarm Maul and capture him alive. After that... it is quite possible Maul would blurt something out, considering his rage and lack of control. Even Opress could be valuable as prisoner, and events could force Palpatine to prematurely reveal his hand.