Philip Markoff, the accused "Craigslist killer" currently being held in Boston on murder charges, gambled all night at the Foxwoods Casino two days after he allegedly killed Julissa Brisman at an upscale Boston hotel, leaving with $5,300 in winnings, a source with knowledge of the investigation told ABC News.
He also gambled at the Connecticut casino two days after he allegedly attacked another woman at the Westin Hotel in Boston, said the source, who spoke to ABC News on the condition of anonymity. Prosecutors claim he stole $800 out of the woman's wallet before he bound her, duct-taped her mouth shut and then used plastic flexi-cuffs to tie her to a doorknob.
Markoff, a 22-year-old medical student, pleaded not guilty today to robbery, kidnapping and murder charges and was ordered held without bail.
A police source close to the investigation told ABC News this week that police believe Markoff's motive in the alleged crimes was to pay off gambling debts. Suffolk District Attorney Daniel Conley, speaking to reporters today after Markoff's brief court hearing, would not comment on the gambling allegations, but said authorities believe robbery was the motive for the crimes.
Markoff opened an account at the Foxwoods casino in 2008, but his visits to the casino increased "in March and April," leading the Cheryl, N.Y., native to apply for a credit line in early April, a source with knowledge of the investigation said.
"He went to Foxwoods frequently, including visits on April 2, 12, and 16,'' the source told ABC News. "On the 16th he left with $5,300 in winnings.''
Markoff also used his hometown New York address at 803 Cheryl Rd. and the Quincy, Mass., apartment he shared with his fiancée to apply for a credit line. The highest single bet Markoff made was $1,000, the source said.
"He came once in 2008, but then he was here all the time starting in March,'' the source said.
Police say the clean-cut 22-year-old robbed two women he solicited through personal ads on Craigslist.
Prosecutors said today that Markoff bound and robbed a woman at the Westin Hotel on April 10. In a separate April 14 attack, prosecutors claim Markoff tried to rob 26-year-old Brisman at the Boston Mariott Copley Place Hotel, but hit her over the head and then shot her in the heart when she resisted.
"This is a brutal, vicious, savage attack. This suspect showed he was willing to take advantage of women," said Conley, adding that there was a "strong possibility he has done this before."
During a search of Markoff's house, police found a semi-automatic weapon, plastic ties and duct tape, Conley said.
He added that there is a "strong possibility" that Markoff has attacked other women and asked other potential victims to come forward.
Authorities said they followed cell phone and computer records to Markoff, linking an e-mail account used to set up appointments on Craigslist with the two women who were attacked to his address in Quincy, Mass.
Markoff, dressed in khakis and a button-down shirt, did not say anything during the brief hearing. His attorney, John Salsberg, said his client was not guilty.
"Philip Markoff is not guilty. He has his family's support," he said. "All I have is words and that's not proof of anything."
Markoff's fiancee, Megan McAllister, who lived with him, told ABC News that police have got the wrong guy.
"Unfortunately, you were given wrong information as was the public," McAllister wrote to ABC News in an e-mail. "All I have to say to you is Philip is a beautiful person inside and out and could not hurt a fly! A police officer in Boston (or many) is trying to make big bucks by selling this false story to the TV stations. What else is new?? Philip is an intelligent man who is just trying to live his life so if you could leave us alone we would greatly appreciate it. We expect to marry in August and share and wonderful, meaningful life together."
Police said they tracked Markoff down using surveillance videos at three hotels. In photos taken from hotel cameras, the man police have been seeking in connection with the crimes appears to be fixated on a BlackBerry. Investigators said that Blackberry is what led them to Markoff.
A police source close to the investigation said cops found Markoff by tracing Craigslist e-mails.
"They followed high-tech leads and old-fashioned shoe leather," Suffolk County District Attorney Dan Conley said in a news conference. "They've connected IP addresses and physical locations."
Markoff's friends and neighbors are shocked. After all, Markoff, a second-year medical student at Boston University, had no criminal history and was engaged to be married to a woman he met more than three years ago when they were volunteers in an emergency room. The university suspended Markoff after learning of the charges against him, a school spokeswoman said.
"I can't even put it into words, the disbelief I'm putting into works right now," Markoff's friend Jonathan Uva told "Good Morning America" today. "It's just a total disconnect from what we're hearing in the news."
Uva, who lives next door to Markoff in Quincy, Mass., said he went to sleep last night listening to police searching his friend's apartment.
"I'm a little unsettled, definitely," he said.
Another friend, Mike Dye, told "Good Morning America" that he'd had Markoff over to his apartment for parties and for the Super Bowl.
"I like to think I'm a good judge of character, hang out with people who are similar to myself," he said. "Didn't suspect anything like that."
"I would never believe this would be something he would do," friend Kym Direnzo said on "GMA."
Markoff's Facebook profile lists hundreds of friends who attend schools in Boston and upstate New York.
But for all the nice things they had to say about Markoff, his friends said there was a bit of mystery about him, though nothing overtly nefarious.
Friends said they didn't even know he and McAllister were engaged. Though they agreed they seemed like a nice normal couple, his friends said they thought the two were simply dating.
"He very rarely talked about himself," Uva said.
The couple's Web site, once flooded with well wishes from friends and family, is now filled with cruel postings from strangers, many directed at McAllister.
The site had detailed how they met when McAllister was a senior at the University of Albany and Markoff a sophomore. Their wedding date was set for Aug. 14.
Markoff's arrest came just hours after Warwick, R.I., police released new pictures of the man they believe is responsible for the attempted robbery of a woman at a Holiday Inn there last week.
Police in both Boston and Rhode Island have said they believe the attacks may have been carried out by the same person.
On Monday, investigators released a clear photograph of the suspect taken during the most recent attack in Warwick. A series of images show the suspect inside the Holiday Inn Express Hotel last Thursday evening, the scene of an attempted robbery of a woman.
The man seen in the pictures taken in the hotel closely resembles the man seen in a surveillance camera photo that was released after Brisman was found dead just days earlier.
Detectives have also a match among plastic zip-tie cuffs used to bind all three women. Two law enforcement sources told ABC News that the plastic restraints were being investigated after they were used to bind the hands of the victims.
"Detectives are aggressively pursuing a number of promising leads," Boston Police Department spokeswoman Elaine Driscoll told ABC News earlier today, refusing to comment on the plastic cuffs.
The man captured on a series of surveillance cameras in Boston's upscale Back Bay was a 20-something, clean-cut blond man who was seen leaving a luxury hotel where police said Brisman, a masseuse, was shot and killed just moments before in her room.
Brisman's death is the second in a series of crimes against women who police say advertised on Craigslist.
The first crime happened Friday, April 10, at the Copley Square Westin hotel in Boston. Police say a woman who had advertised exotic services on Craigslist, was held at gunpoint, bound and robbed of $800.
Then, Tuesday night, April 14, Brisman was killed at the Marriott, just next door.
Finally, late Thursday night -- an hour south in Rhode Island -- there was a similar attempted robbery.
Police said all the women were tied up and threatened at gunpoint. It is believed that Brisman may have tried to resist her attacker as he tried to bind her wrists, and was shot.
Boston police are working with police in Rhode Island to determine if the cases are connected.
A common thread among all of the victims is that they all had posted Craigslist advertisements for some sort of massage or exotic dance. Investigators say that's a vulnerable venue to offer personal services.
Former FBI agent and ABC News law enforcement expert Brad Garrett said Craigslist is a first choice for many looking for sexual services.
"By some sources, it's one of the leading avenues to promote prostitution because it's so easy," he said. "You place an ad, you say, 'Come to Hotel X, at a time and date' and a service is provided. It's really an ideal environment for criminals."
Earlier this year, New York radio anchor George Weber was murdered in his Brooklyn apartment, and police said they believe the killer answered Weber's Craigslist advertisement offering $60 for "rough sex." Weber was stabbed more than 50 times.
Gay Talese, an author who writes on the sex trade, whose most popular book, "Thy Neighbor's Wife," came out long before sites like Craigslist existed, said such sites are making the problem much bigger because the players are anonymous.
"It's instant communication, it's instant sex, it's sometimes instantaneously a tragic situation," Talese said. "The reason it's definitely bigger is because any sense of caution or guilt associated with sexual interchange of a commercial nature is eliminated now."
Just last November, Craigslist entered into an agreement with 40 state attorneys general to eliminate some of the anonymity by requiring credit cards to post these erotic ads.
The company CEO told ABC News they are deeply saddened by the events and are "evaluating the incident to see if they can better protect Craigslist users."
But experts say little can be done to prevent criminals from using the Internet to stalk their prey.
After the arrest today, Craigslist CEO Jim Buckmaster issued a statement, saying, "We are very pleased to hear that the person alleged to have committed these crimes has been arrested, and we will continue to provide law enforcement agencies with any assistance necessary to prosecution of the case."
ABC News' Scott Michels contributed reporting to this story.