From the existing situation, it's very likely that the kidnapper abducted the child from Maria's home, with the purpose of threatening her to kill George.
With Luke's experience, he guessed that the kidnapper staying at Maria's house was improbable.
The reason was simple, since Maria was coerced, no one could guarantee that she wouldn't call the police.
Even if she didn't call the police, it was very likely that Maria would be arrested.
Therefore, the kidnapper continuing to stay at Maria's house was unlikely.
However, the first direction of the investigation was directed at Maria's house; since the kidnapper had been there, it was very possible that some evidence might have been left behind.
Secondly, the previous statement was only Maria's side of the story, and Luke couldn't possibly trust her without any reservations.
Apart from Luke and Xiao Hei, there were also Raymond, Jenny, and several patrol officers on the scene.
