How long did Thomas know?

[Mira]

Lara never saw through Justine's ruse in what 48 hours?

No, she didn't, okay, cut her some slack for that, but how about before when she was close as
her secretary and confidant? 

[morriswalters]

Nemesis isn't tied to any body.  All he has to do,  assuming he was locked to Justine in the first place, is have her take a short walk off a tall building. All the power Nemesis holds in his possession of Justine is his presence here and the power of the baby. Given the way Jim likes to torment Harry you should be able to guess one way that might turn out.

[Ed0517]

I'd have to reread  - but wouldn't they have a good chance to get Justine on Demonreach either way?  Thomas gets away with the attempt, successful or not, he is looking to hide. She gets a visit. He gets caught/killed in the attempt, successful or not, she is Scared, afraid of retribution, and turns to her (almost) brother in law for protection for her and her baby, his niece/nephew. If Harry hadn't put things together - she's there either way