If anyone needs any help with Sherlock Holmes: The Mystery of the Persian Carpet please post here.

There is a walkthrough HERE.

Many of your questions may already be answered
Here as well or Here.
Ana

The victim and suspect already have a green line connection. The victim and the time of death and knife also have a green line connection.

1. Click on Richmond Alley hideout at bottom right area. Click on the knife and then click on the knife at center of the frame.

The knife in Richmond Alley hideout connects to the knife that is the murder weapon.

2. Click on the top footprint in Richmond Alley evidences and then click on the footprint of the victim at top of the screen.

The top footprint in Richmond Alley hideout matches to the footprint of Vincent the victim.

3. Open Lord Layton on the suspects at left area. Click on the expensive cigar and then click on the cigar ash at evidences of Richmond Alley hideout.

The cigar ash found behind the screen in Richmond Alley hideout matches the expensive cigar of Lord Layton.

4. Click on opera paper of Lord Layton as suspect and then click on the clock at center of the screen.

The opera paper of Lord Layton connects to the clock (time of death).