You’ve been called to the scene of a murder. the lock on the victim’s apartment door was broken, likely by a crowbar found in the doorway. the victim was found lying face down on the floor with a bullet in his back. based on the condition of the apartment, it appears a struggle occurred between the victim and the murderer. there are several drops of blood located in the nearby kitchen, as well as a broken glass on the floor. assuming this situation occurred in the late 1800s, which relatively new type of evidence would most likely be used to identify the killer?
dna samples taken from the hair and blood found on the floor
motives of possible suspects based on information from the victim’s wife
fingerprints found on the crowbar and on the glass
information obtained after examining the bullet under a comparison microscope

i think its the "motives of possible suspects based on information from the victims wife"

THIS IS HOW IT WORKED BACK THEN!!: they would First likely examine the bullet and then find out what gun model it belongs to then they would find the registered list of everyone with that gun and link possible suspects based off of that (which are related to the victim) thus would be looking for the killer based off of the victims life so the only option i see fit is the on i put in bold above   this is just my opinion though!

they deliver oxygen to the blood

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.