Showing Mars the Avenger by Alan Scribner

"Mars the Avenger" is an historical mystery set in the year 158 CE, during the reign of Antoninus Pius, a period often called the height of the Roman Empire. It is also a daily life in ancient Rome and a sojourn into the world of Roman life, criminal law, police and courts.
Marcus Flavius Severus, a judge in the court of the Prefect of the City of Rome, investigates the disappearance of a senator's wife and the finding of the body of a murdered man thrown on the steps of the Temple of Mars the Avenger. As the investigation unfolds, the two cases become connected to a love affair seventeen years before in the Roman orient.
The investigation leads Judge Severus and his court and police aids through the City and the society of ancient Rome, into a slave market, wealthy villas, taverns, tenement apartment houses and the Circus Maximus. There are also scenes in Roman courts and the book is accurate as to the criminal laws of the time, including the use of judicial torture. All laws, rescripts and legal procedures are from Roman law sources.
The novel also introduces a perspicacious new detective in the person of Roman judge Marcus Flavius Severus.