In the era of Jack the Ripper, this allowed him to walk the streets freely. Holmes used methods he himself introduced in the late 19th century and which have proven to help evolve the methods of scientific investigation we use to catch criminals today. Modern detectives consider Arthur Conan Doyle a genius. Holmes used methods such as chemistry, fingerprints and bloodstains to catch criminals. Holmes was the first to use ballistics, which included bullet trajectory, used as evidence in criminal cases. Holmes pioneered modern toxicologists by using scientific methods to detect the presence of poisons during the late 19th century. Doyle's popularity gradually increased along with Sherlock Holmes and, as a creator of short stories, he received letters asking for help with crimes. In 1903, Doyle exonerated a man accused of killing animals and proved the accused's innocence, but the police refused to believe him. As Doyle's voice became increasingly influential throughout the 20th century, he played an important role in the creation of the British Court of Justice