Monitor someone who they wanted to recruit until they could
1) find an accusation for which the target would have no alibi (although they were clearly innocent)
2) confront the target with the accusation and the penalties for it,
3) say that (as an agent) "I personally think that you are innocent although you have no alibi and would have to be found guilty if reported,
4) "but to prove your loyalty, you could help us just this once in our fight against the criminals we just accused you of working with."