Why in Season 3 episode 18 Tony says that Special Agent Caitlin Todd is on the case even though she is dead that really confused me??

Tony says that Kate is looknig for the boys mother to let Gibbs know that she was dead. When he a dit that Gibbs knew that she had died because Kate was dead,and the kid didnt know Kate was dead was he figured that she was actually on the case.

It's because he's trying to convey the message to Gibbs that the hostage-holder's mother is dead. He a dit Kate was picking the mom up so that Gibbs would understand that the mom was dead.

He a dit this to let Gibbs Know that the boys mother was dead.

it had been a way for Gibbs to be able to get information on the Kody's mother. It had been code, stating that she was dead, just like special agent caitlin todd is.

To let Gibbs, know that the kids mother is dead