A house was robbed last night. The robber left a note in a strange code, reading ''????''. There are 3 suspects: Ella, James, and Julian. The police were unable to decode the symbols, but arrested one of the suspects immediately after they were presented. How?

Without knowing what the symbols meant. they knew each symbol stood for a letter. There were four symbols written on the note, and only one suspect with four letters in their name. Therefore, the police arrested Ella. For further proof, the symbol ? was repeated twice in the same place where the letter "l" was repeated twice in Ella's name.
(I'm sorry if this was bad, I made this up myself and I've never really made up my own riddles :) )