Here is the list of evidence you need to look at and or pick up and process in Leda's Swan Song. Note: some of the evidence is from the previous case, and will be given to you by Brass once you have connected the cases together enough to need the previous evidence.
I have listed everything by location and the relative order in which you can get the evidence. Items with trace evidence on it have ---trace beside it.
I have not included what to do with the evidence, or questions that are triggered by the evidence- you'll have to figure that out yourself [or look at the more detailed walkthroughs] 
Enjoy!!
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LEDA's APARTMENT
A. On table (left side of room)
keys
large piece of paper
small piece of paper ---- trace
B. photo album
dark spot on left page ---trace
right page
C. SOFA AREA
cellphone ---trace
poker chips
D. CABINET AREAS
bottle on shelf
open cabinet : look at book
smeared substance
DESERT DEMONSTRATION GARDENS
shoe print
bug sample
tire tread (in front of post)
paint chip in lamp post
BRASS: GET OLDER EVIDENCE from previous case. REMEMBER TO GO BACK TO LAB TO PROCESS EVERYTHING!
CHAMPAGNE HOTEL
smear on window sill
KAREN's APARTMENT
computer schedule [should print automatically if you have all previous evidence and all questions asked up to this point]
STORAGE LOT - not evidence, but you need to use these.
dumpster pipe
55 gal. drum (rear of lot)
*** There is a lot of lab work in this case- lots of comparisons in the computer and searches.
*** There is also a lot of questions to ask in this case- so be sure to ask Leda, the doctor, etc. as well as Brass as much as possible. I did not list the times when new questions pop up in this list.