If the detective does not want to sign an agreement, then you should think twice before hiring him. Do not hesitate to ask the detective how many cases he has handled in the last six months. Make sure that he uses modern techniques in solving cases. You should try to understand his techniques and try to know how he would handle the case. You can ask him what methods and techniques will he use for your case. It is very important that the detective keeps the case details confidential. You should clarify these things before hiring the right detective. You can also mention the same in the contract to avoid confusion later on. Hiring the right private detective for investigations can be stress-free. They should gather the required facts and evidence for your case. He can even testify or provide evidence in a court of law.