Just a Corpse at Twilight by Janwillem van de Wetering

In the twelfth book in an acclaimed series, retired Amsterdam policeman Henk Grijpstra gets a frantic telephone call from his old partner, Rinus de Gier, who thinks he may have killed his girlfriend.He is being blackmailed and can’t remember if he did it; he was just too drunk. But if he did, where is the corpse? Would his old partner please fly over to the US at once? Urged on by their former superior officer, the commissaris, Grijpstra grudgingly travels to Maine to rescue his partner and to confront his own demons as well as de Gier’s.