The Locked Room: The Story of a Crime by Maj Sjowall and Per Wahloo (1973

 Suddenly he remembered his own experiences in this field.  Almost twenty years ago, right after he got married, he'd been very hard up.  Before Inga -- the cause of the marriage -- was born, his wife had been working for an insurance company.  There she had been able to buy at a discount a great number of cans of unusually foul-tasting consomme damaged in transit.  They'd lived on them for months.  Since then he'd never really liked consomme.  Maybe the loathsome liquid had already been tasted by Kalle Svard or some other expert and found unsuitable for human consumption. 

--The Locked Room by Per Wahloo and Maj Sjowall (Random House, 1973, translated from the Swedish by Paul Britten Austin)

This is the eighth of ten novels that Wahloo and Sjowall wrote about Stockholm's police, with an emphasis on Detective Martin Beck.  Beck is back at work fifteen months after being shot and in The Locked Room he is investigating and solving the murder in a locked room of Kalle Svard, a reclusive retired worker.  In this investigation he overlaps with The National Homicide Squad in their botched attempts to solve a bank robbery in which a bank patron was killed.  Wahlool and Sjowall contrast Beck's detailed analysis and research with the Keystone-Cops-type of investigation by the Squad and its temporary leader, Bulldozer Olsson, a district attorney who is fascinated by bank robbery.

The Locked Room contrasts Beck's methodical investigation with the guesswork of the Olsson-led squad as both Beck and Olsson end up with the same man as their leading suspect, who gets convicted for the bank robbery -- which he didn't do-- and acquitted of the murder of the man in the locked room who had been blackmailing him, which he did do.  Throughout the novel Wahloo and Sjowall take a close look at Swedish policing and Swedish society, where criminals are not caught and housing is becoming unaffordable. In the course of his investigation the now-divorced Beck meets a woman, Rhea Nielsen, who charms him with her intelligence and independence and who he continues to see, as the personal and professional overlap.