BOSTON , Massachusetts ( CNN ) -- They were crimes born of the Internet age -- romantic solicitations on popular Web site Craigslist that police say led to the fatal shooting of one woman and the robbery of another in Boston hotels this past spring . Internet forensic expert Mark Rasch used high-tech sleuthing to help police in Boston 's Craigslist crimes . And it was high-tech , 21st-century sleuthing , along with some old-fashioned gumshoe detective work , that put police on the trail toward a suspect and eventually an arrest . On CNN 's `` AC 360 '' Randi Kaye recently took a behind-the-scenes look at how technology was used to lead police to 23-year-old medical student Philip Markoff , who has been indicted on seven counts , including first-degree murder . Prosecutors said Julissa Brisman , a model from New York who advertised as a masseuse on Craigslist , was shot three times at close range and suffered blunt head trauma at the Marriott Copley Place hotel on April 14 . And a 29-year-old Las Vegas , Nevada , woman was robbed of $ 800 in cash and $ 250 in American Express gift cards at the Westin Copley Place hotel , police reports said . Read the AC360 blog post . Investigators knew they had crimes born of the Internet on their hands , but how were they able to use that same technology to help them find a suspect who went to great lengths to hide his tracks ? `` The figures involved communicated with each other [ via ] text and e-mail , and they only met at the very last minute , '' said special correspondent Maureen Orth , who investigated the story for Vanity Fair magazine . `` And then the way the police were able to solve the crime was going back , using the clicks and the Internet addresses . '' In Brisman 's case , police knew she had communicated on Craigslist with a person calling himself `` Andy . '' Mark Rasch once headed the computer crimes unit at the U.S. Department of Justice . Now an Internet forensic expert , he helped Boston police track the alleged killer . `` The first thing you start with was the e-mail address . In this case , it 's an e-mail address from Live.com , which is Microsoft , '' Rasch explained to CNN 's Kaye . Watch Randi Kaye 's full report » . Rasch showed Kaye the tracer program he used to help follow the e-mails from `` Andy . '' `` Trace Back does what it says -- traces the route that the e-mail took on its way from its origin to the destination , '' Rasch said . Rasch says police got the Internet protocol address for the e-mailer 's computer . From there , investigators tracked down the company providing Internet service to the suspect , which told them that the subscriber lived in a Quincy apartment building , outside Boston . Even though police had what they believed was the killer 's real name and home address , that still was not enough , Kaye reports . `` They have to validate and actually get this guy 's fingers on the keyboard , '' Rasch said . `` So in the end , they reverted to the old gumshoe thing of a stakeout . '' Police zeroed in on Markoff . They 'd seen a tall , blond male they believed was the killer on the hotel surveillance cameras . And they did what many people do on a daily basis -- they Googled him . Police learned their prime suspect was a medical student at Boston University . He was engaged to be married . Again , the Internet helped . They got a better look at him through pictures with his fiancee online . It 's a piece of a digital trail criminals rarely think about , Kaye reported . `` As one of the law enforcement people told me , if you can see it , they can see it , '' Orth said . Markoff 's cyber footprint was growing more clear to authorities every day . On April 20 , six days after Brisman 's slaying , detectives arrested him . They said he was carrying on him a New York driver 's license with a photo of someone named Andrew or Andy Miller . Police say Markoff used that driver 's license to purchase the gun that killed Brisman and that his fingerprints were on the paperwork . In June , Markoff pleaded not guilty to Brisman 's death and the other charges against him . He remains in jail . CNN 's Randi Kaye contributed to this report .
Internet expert : Craigslist slaying suspect left a trail of clues behind in cyberspace . Mark Rasch says he used a tracer program on e-mail sent to slaying victim . Boston investigators even used a Google search to help track down suspect . Philip Markoff , a medical student , pleaded not guilty in death of Julissa Brisman .