Done: Tequila Sunset by Sam Hawken, 2012, 9781846688546.
This started off too slow for me but I kept reading I ended up really enjoying the novel.
Flip Morales just did four years in a Texas prison and is back home in El Paso. Flip is an okay guy but took a rap for something he was only partially involved in (I cannot recall what). Part of prison survival required joining the Aztecas for protection. Part of joining required knifing another prisoner. Flip didn't kill the other man but from then on was regarded as a sold Azteca and under the wing of the gang's ultimate leader.
El Paso Police Detective Christina works a gang unit. El Paso is low crime and most cops seem focused on Honeland Security issues. Christina and her partner do not have many bad guys to chase but they do have a local Azteca gang leader, Jose, that they are after.
Meanwhile, Mexican police officer Matias works in Ciudad Juarez. Ciudad Juarez would be a dreamworld for Alex and his Droogs. Matias doesn't work murders, Matias works mass murders. Matias works beheadings. Matias works torture cases with victims burned in bonfires. Matias's interrogations are preceded by his interviewees enduring beatings by Matias's colleagues. Matias is working a Los Aztecas cases related to the ongoing drug wars.
All three sides mix together as Flip is pulled into the gang by local leader Jose. Flip wants nothing to do with crime and decides to inform on the gang the same way he did when he was in prison. Christina and Matias meet after Christina and her partner are joined with a Federal task force. The American task force is going to bust the Americans for exporting guns and importing drugs as the Mexican Police bust the Mexicans for exporting drugs and importing guns.
Many things happen. Matias is a dedicated and honest cop - he and his colleagues are not the badge carrying Mexican crooks of cinema with sweaty faces and mustached lips. Matias works long hours and he and his wife survive an assassination attempt. Matias greatly misses his wife after she flees Ciudad Juarez to stay with her sister in Monterrey.
Flip meets a girl and falls in love. He wants to keep his new job at a food warehouse and stay out of trouble but Jose wants him to work. Jose is pressuring Flip's straight arrow boss, also the new boyfriend of Flip's mother, to allow drug carrying produce trucks to unload dope at the warehouse.
Christina gets home tired and worn out and relieves her son's sitter. Her autistic son, Freddie, is a worry. Freddie has trouble in school, requires a strict schedule, and when at home he just wants to play Minecraft all night. Christina is single and her life is either work or caring for Freddie. When Los Aztecas start targeting cops she gets anxious.
There is not a lot of street crime here. No inside look at gang life. No chases. Only a couple shoot-outs. No tough talk and posturing. People care for each other and work to get ahead. The gang pursues violence but members think of themselves as family. The gang hosts large barbecues and neighborhood parties.