Beat Cop

First off, you need to reach 100 reputation with the mob.

The mob has their turf on the west (left) side of the beat, so you usually find their jobs there.

Day 2 - Talk to the mobster in the pizzeria, get a tip on the pawn shop. After lunch a greaseball shows up outside Matthias workshop for a courier job. You pick up a package at 611 from Venkman. To be dropped off at 631, Ramirez. Delivery will give you (+5 Mafia).
Day 3 - Talk to the mobster outside the pizzeria. Then go inside and talk to the boss. He'll give you a mission to get rid of a Crodillac Shipwood at 4:00 PM. Write a ticket for the car parked outside the pizzeria at four, don't take the bribe the owner is offering and then talk to the mobster in the pizzeria for a (+5 Mafia). (10 total).
Day 4 - Talk to guy in a suit outside pizzeria. Talk to Louis inside pizzeria. You need to search the grey van ouside the Pawnshop. Move the tire, take the package and deliver it to Louis at the pizzeria for (+5 Mafia) (15 total)
Day 5 - You get a call about the mob extorting businesses in the neighbourhood. Walk into both places (Donuts and diner) and talk to the mobs, but walk out/back off when you get the option. For looking the other way you get (+10 Mafia x2). (+35 total).
Around 11 AM you should talk to the mob outside the pizzeria . You'll get a mission to find a black Crocodille, licence JA-382T. You find it outside the pawnshop. Tell Louis in the pizzeria for (+10 Mafia) (+45 total) Late during the day on the far west outside 601, the mobs are annoyed about a ganger selling drugs. Let the mobster deal with him and get (+10 Mafia) (+55 total)
Day 6 - Outside the pizzeria is a mobster you should talk to. He´ll want you to look for a tricycle. You find it outside the Hifi-shop in the east end. Don't arrest or report the drugs on the bike. Report back to the mob outside the pizzeria for (+10 Mafia) (+65 total).
Day 7 - Outside pizzeria you find a mob in a suit. He wants you to clear a parking space and remove hookers and dealers from the vicinity around 3:30. Remove the two dealers to the right of the pizzeria. Don't take their offer. Then talk to the hooker in the pink dress in the alley and pick 'insist' to remove her. And just ticket and tow the car that parks outside the pizzeria. You'll get (+10 Mafia) (+75 total)
Day 8 - Outside the pizzeria, talk to the guy in a suit. He'll want you to remove bugs from the phone booths. Visit all phonebooths and dont give them to the gang member approaching you. Give the bugs to the mobster at the pizzeria and get (+5 Mafia) (+80 total).
Day 9 - Talk to Louie at the pizzeria. He wants you to sort out the establishment next door. Go to Hard Ricks cafe and talk. Choose to 'insist' and get (+5 Mafia) (+85 Total) On the same day you get a call about extorsion. same procedure at Jewelry and Kranks drugstore will get you (+20 Mafia) ( +100 Total - MAX)

Now talk to the mobster outside the pizzeria and get invited into the pizzeria. There you accept the offer and the achievement is yours.

For this achievement you need reach 100 reputation with the mob.

Each day you'll usually find at least one activity that you can do for either the mafia, or the crew. Completing jobs and accepting deals from the mob will increase your reputation.

When you reach 100, go to the pizza restaurant and they'll make you an offer you can't refuse. Well, you can refuse, but don't and you'll earn this achievement.

It also takes you to a game over screen, so select the rewind time option from the menu and replay the day to continue the story.

Very simple max your reputation out with the mafia and go into louie's, when you do you work for them permanently winning this achievement and ending.