‘I don’t know,’ Marta said. ‘You’re the policeman. You go and find the murderer. But I can tell you one thing. You can begin with the new President. He’s got a murderer’s face.’
Assuming that we know that the policeman is Felix. Which question is the correct one?
1. Where did Marta believe Felix should start his search for the murderer?
With the new President. / He should start it with the new President.
2. How did Marta believe Felix should start his search for the murderer?
With the new president.
For the first part, you could also ask "What did Marta think was Felix's job to do?"
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
His job was to find the murderer. It was suggested to him that he begin with the President.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.