ANSWER
In the first place once we interrogated the personand once we gained the information, this person's, the peoplewho gave this person instructions would have known what informationthis person had access to, they would therefore have changed theirplans.   Terrorists of whom they knew would have escaped and goneinto hiding in different places.   We also had to protect ourinformants because the person would have been able to point outour informants and we had to protect our informants.