Powerful ending to section 7 of Alexanderplatz - Berlin: lest we forget, these are bad guys

It's easy to forget, as you're reading Alfed Doblin's Alexanderplatz - Berlin, that the seemingly hapless and feckless low-life  protagonist, Franz Biberkopf, is actually a very mean and dangerous man. We meet him when he is released from prison after serving time (4 years!) for killing his girlfriend, Ida. Over the course of the next several hundred pages he seems so set upon and luckless that we forget the sins of his past and see him as a guy with no family, no friends, no education, no chance - he struggles to make an honest living, gets drawn into a couple of petty criminal enterprises that end up costing him his right arm, gets involved with a series of short-term relationships - for some reason women seem really attracted to him - and we begin to think, yes, he's part of the exploited underclass. In previous posts I've compared him to heroes from Camus and Steinbeck. But let's not get carried away: He's a bad guy, and we see more of this in "book" 7 as he gets jealous of his girlfriend - a prostitute who turns over to him all her earnings, as he does nothing to earn even a dishonest living - and beats the hell out of her. And then they reconcile and embrace. Tough guy. The last section of this "book" is extremely powerful, the best and so far the most painful part of the novel, as the girlfriend, Mietze (aka Sonia) goes off with one of Franz's buddies, Reinhold, who tries to have sex with her (she's been pretty loose w/ a lot of guys and he and Franz have a history of passing "janes" on to one another); she resists and he brutally kills her, then buries her in a wooded area and takes off (sounds like The Serial?). Doblin does a great job with the fast pace of narration of this section, moving fluidly from the voices/dialogue of the two character, the interior thoughts of Mietze (the closest he comes to Joycean narrative), and a strange, omniscient observer who repeats, among other things a haunting rhyme, There is a mower, death yclpete.