Lawrence Grayson was a former Green Beret.
At some point, he joined the army and was a member of the Green Berets. He also collected several weapons, as well as started his own security firm. He also had a pet Rottweiler dog, which he was led to believe was a prized showdog.
In 2002, he hired Pratt, an attourney to help him with a property dispute with his neighbor, Monica Waters, due to her building her garage very close to his property, offering a sum of forty dollars if he wins the case. However, Pratt and his secretary were murdered before the trials, and he was considered a suspect because the person who broke into the office as well as murdered Pratt as well as his secretary broke into the filing room as well as burned a file, and the file that was burned belonged to Grayson, and it was suspected that he had some sort of grudge against Pratt. The Police also confiscated most of his belongings because he was a suspect.
Monk noticed some details that made him doubt that Grayson killed the guy: For one thing, due to his leading a security firm, he would also know how to properly unlock a door and thus would not have had to break a window to open the door, the second issue was that he formerly served in the Green Berets, which were a special forces group which required a lot of conditioning and training, and thus wouldn't make sense for him to struggle for at least three minutes in killing Pratt, who would have been severely outmatched by Grayson if he was killed by him.
Grayson was later murdered by the same person later on, by taking his Rottweiler to Waters' garage to lure him to the garage and then fatally hit him with a shovel, which also cleared his name as a suspect. The murders were later revealed to have been committed by Tod Katterskill.