Classic literature can be a great source. Names from detective novels like 'Hercule' from Agatha Christie's works. Mythology is also good. For example, 'Athena' could be a strong, intelligent female character's name. And historical figures. Names like 'Caesar' can add a sense of grandeur and mystery.
One important name is Sam Spade from 'The Maltese Falcon'. He is a tough private detective who gets caught up in a web of lies and deceit while searching for a valuable statuette.
You could use names that have a certain mystery or enigma to them. For example, names that are old-fashioned or not very common. Or you can look at different cultures and use names from there. Another option is to play with words, like using anagrams or words with double meanings as names.
Some good character names for a mystery story might be 'Oliver Twistlock'. The name 'Oliver' is common yet can be made mysterious with the addition of 'Twistlock'. It makes you wonder what secrets he might be twisting away. Then there's 'Scarlett Enigma'. 'Scarlett' is a vibrant name, but when paired with 'Enigma', it becomes a character full of mystery. Also, 'Professor Riddleford' could be a great name for an intelligent and mysterious character who is always full of riddles.
In a mystery story, 'Detective Blackwood' is a classic - the name 'Blackwood' gives an air of mystery. 'Scarlett Lane' could be a femme fatale type of character. And 'Mason Gray' sounds like a noir - ish, mysterious detective.
For a victim, how about 'Ella Gray'? The name 'Ella' is soft and feminine, which makes her seem more vulnerable, and 'Gray' can add a bit of a dull, tragic undertone. As for a suspect, 'Maxwell Stone' could work. 'Maxwell' sounds strong and confident, and 'Stone' gives an impression of coldness and hardness.
Think about the setting. For a mystery set in an old castle, 'Mystery in the Castle Walls' could be a name. Also, consider using words that create a sense of mystery like 'shadow', 'enigma', 'riddle'. For instance, 'The Enigma of the Haunted Mansion' combines the idea of mystery and a spooky setting.
Some names like 'The Hidden Truth', 'The Mysterious Disappearance', and 'The Puzzle of the Old House' are great for mystery stories. They give a sense of intrigue and secrecy, which are key elements in mystery stories. For example, 'The Hidden Truth' makes readers wonder what that truth is and what events are leading to its discovery.