Do I owe the auto accident lawyer anything?

I spoke with the lawyer, about my accident, over the phone. He provides free consultation. I also met with the lawyers "investigator" and asked if there would be a fee for meeting with them. I was told that I may have to pay the mileage for the investigator coming to my house. They drove 10 miles to my house. I have not signed anything with the lawyer, nor have I agree to take on their service. They sent me four letters in the mail, two of which simply stated that they would like to represent me. If I don't sign the doent, agreeing to take the lawyer's service, would I owe the lawyer any money at this point?