The Perfect Crime

1. This is the first victim you'll find after getting the mission. Head to Merchant Bridge and examine the body. After analyzing the blood of the victim, you have to use the Deep Tissue Scanner. Scan the victim's skin first then press and hold X to get it as evidence. Next, change the Scan Level to “Muscle” and check the victim's small intestine to find a ring. Scan it again.
   

   Finally, change the Scan level to “Bone” and check the victim's left hip to find the victim's hip replacement. This will complete the crime scene. The next part of this mission will become available once you unlock the next district of Gotham.

   

2. One of the bodies is located on top of the Gotham Herald, on the lower rooftop below the tower. Like before, you have to use the Deep Tissue Scanner to find notable markings on the body.
   
   • Skin level – Scar issue on the left arm
   • Muscle – pacemaker remains on the left chest
   • Bone - Bone deformation on left knee.
   

3. This body is located on the rooftop the Heavenly building in Miagani Island. Use the Deep Tissue Scanner on the indicated portions below of the victim's body.
   • Skin – Birthmark on the chest
   • Muscle – Bullet on the right bicep
   • Bone – Missing toes on the left foot.
   
   

4. The next intel will become available after helping Ivy grow her plant to help neutralize Scarecrow's toxin. It's located on top of a small building NW of the orphanage, right under the railway. Scan the following:
   • Skin – Bite mark scar on the left side of the victim
   • Muscle – False right eye prosthetic
   • Bone – Fractured right arm.
   

5. This body is located in the lower streets a bit to the SE of Stagg Airship Beta. Scan the following:
   • Skin – Chemical burn on the left thigh
   • Muscle – Voice box on the throat
   • Bone – Six fingers on her left hand
   

6. This corpse is found on the wall beside the ramp, near the divinity church. Scan the following parts to get the clues needed to identify the victim.
   • Skin – tattoo removal wound on the right thigh
   • Muscle – Missing kidney to the right
   • Head – Tantalum plate on the victim's skull.
   

After investigating the last victim, Alfred will be able to give you the location of the suspect. Head to the Pretty Dolls Salon marked in your map. Enter the Salon. You'll also find a Riddler Trophy inside. You can access it by entering the floor grate and blasting away the cracked wall.

Backtrack and enter the main door to the operating theater. Continue forth and you'll find the weirdo in the middle of operation. Approach him to trigger a cutscene. His minions are immune to pain so you have to make them stay down by performing takedowns and environment takedowns. Use normal combo takedowns for the first few minions. Once Pyg calls in all his minions, he'll stay in the operating table. Don't bother approaching him since he'll just run around the corner. You have to eliminate all his minions. You also have to look out for the cleavers he'll throw. You can deflect the two and catch and throw back the third to stun him. It will be hard to perform a combo takedown with the last minion so you'll have to use environment takedown against him. Finally, approach Pyg and perform a takedown on his operating table.

After knocking out Pyg, destroy the electric box nearby to lower the cages containing civilians. Talk to them then pick up Pyg to load him up in the Batmobile. Drive all the way back to GCPD to lock this sick b*stard up and close the case.