Detective John Phillips (who is on the Corleone's payroll and helps them in the McCluskey affair) visits the Adams' family a few days after the murder of McCluskey. Why?
Is it (1) just what we read? He wants to find out from Kay where Michael is hiding? This might be the case because all policemen cut their connections.
Or is it (2) a subtle move of him and Hagen to tell her about Michael? This might be true because he's been on the payroll for a long time, and also he was kind of involved in the killing of McCluskey.

It's the former. Murdering a policeman changes the landscape.

I'm with Oli. The murder of McCluskey would have made catching the perp the Number One priority for all NYC policemen. Plus, Philips would have to look especially vigilent to hde his association with the pre-shooting Corleones.

Old thread: I noticed that during their first tryst after Michael comes back, they talk about marriage and he tells Kay, "I hear your father is a real tough guy in his own way. Listen to his advice." That seems to refer back to the detectives' interview with Kay, and implies that Phillips has been briefing the Corleones about the progress of the investigation.