The Gilgo Beach serial killer suspect owed hundreds of thousands of dollars in taxes and was litigious, filing numerous lawsuits against motorists

• The man suspected in four of the Gilgo Beach murders in Long Island had a history of tax debts and lawsuits.
• Rex Heuermann at one point owed nearly half a million dollars to the IRS, according to county records.
• Heuermann was also litigious — he filed four lawsuits against motorists within eight years.

The Long Island architect charged with killing three women who went missing in 2009 and 2010 has a colorful history of tax debts and lawsuits, according to county and court records.

Rex Heuermann, 59, was arrested Thursday evening and pleaded not guilty at an arraignment on Friday. Prosecutors said they have linked Heuermann to three of the 11 Gilgo Beach murders through DNA evidence found on the victims' bodies.

A fuller picture is rapidly emerging of Heuermann, who presented himself as an amiable policy wonk eager to explain the nuances of New York City building codes. As Insider's Laura Italiano reported, Heuermann excitedly described his work and his skillset during an interview with a French YouTuber last year, which included his ability to persuade others. 

Yet at the same time, Heuermann was known to his neighbors largely for keeping to himself and barely maintaining his dilapidated house.

Public records show Heuermann had a troubled financial history. Heuermann had at one point owed more than $425,000 in taxes to the IRS, according to Nassau County documents. CNN was the first to report the tax liens, which date back to 2005.

Federal tax lien release certificates showed that the IRS ultimately relieved Heuermann of $215,080 of that debt. He still owes just over $210,000.

Heuermann was also highly litigious. Court records show that he filed four lawsuits within eight years against motorists whom he accused of causing "serious injuries," including "great pain and physical and mental anguish." 

In one case, Heuermann accused a woman of striking him in the middle of a crosswalk without braking. The woman argued back that Heuerman had "walked right out in front of [her]" while she was taking a turn at a speed of five miles per hour.

All of the lawsuits, except one that is still open, have since been dismissed or settled. 

Heuermann is accused of killing 24-year-old Melissa Barthelemy, 22-year-old Megan Waterman, and 27-year-old Amber Costello. Authorities also consider him the "prime suspect" in the murder of a fourth woman, 25-year-old Maureen Brainard-Barnes.

Prosecutors said Heuermann "compulsively" searched for pictures of his victims, their relatives, and even their children. They said they found more than 200 internet searches on Heuermann's devices looking up information about the police investigation into the Gilgo Beach murders and how they might try to identify the killer.