Judge Esther Salas' 20-year-old son Daniel was shot multiple times and died at the scene, while her husband -- criminal defense Attorney Mark Anderl -- is in critical but stable condition at the hospital after undergoing surgery, North Brunswick Mayor Francis Womack said.
A body later found at Campsite and Berry Brook roads in Sullivan County, New York, is believed to be the suspect. He was identified as Roy Hollander, a Manhattan lawyer and self-described anti-feminist, multiple law enforcement sources briefed on the case told ABC News.
Hollander's body was discovered by a municipal employee in the town of Rockland. New York State Police were on scene, and the FBI was called.
"A brazen and cowardly act of gun violence at their home in North Brunswick," Governor Phil Murphy said. "We give our full support to Judge Salas and her husband at this most trying time. This is an unconscionable tragedy."
Judge Salas, who is the first Latina to serve on the federal bench in New Jersey, was in the home at the time but was not hurt.
WATCH: NewsCopter 7 over the investigation
Police said the gunman was wearing a face covering and a FedEx uniform, posing as a delivery driver when he arrived at the family home around 5 p.m. Sunday. Authorities say Daniel Anderl opened the door and was immediately shot, with the gunman then wounding Mark Anderl before fleeing the scene.
There was no FedEx truck involved, and the suspect used an ordinary car to make a getaway, sources said.
In a 2015 case before Judge Salas, Hollander represented a woman who wanted to register for the military draft. He was replaced last June as the woman's lawyer before the case was fully resolved.
The court docket did not indicate a reason for his replacement, and the woman's current attorney could not be reached.
Hollander has sued Manhattan nightclubs for favoring women by offering ladies' night discounts and sued the federal government over a law that protects women from violence. He has also sued Columbia University for offering women's studies courses, accusing the school of using government aid to teach a "religionist belief system called feminism."
In 2017, he wrote a letter to then-Attorney General Jeff Sessions in which he complained of living under "Feminazi" rule. He also appeared on ABC News, arguing that Ladies' Nights were unfair.
Just last week, Salas was appointed to hear an ongoing lawsuit brought by Deutsche Bank investors who claim the company made false and misleading statements about its anti-money laundering policies and failed to monitor "high-risk" customers including convicted sex offender Jeffrey Epstein.
Her highest-profile case in recent years was the financial fraud case involving husband-and-wife "Real Housewives of New Jersey" reality TV stars Teresa and Joe Giudice, whom Salas sentenced to prison for crimes including bankruptcy fraud and tax evasion. Salas staggered their sentences so that one of them could be available to take care of their four children.
In 2017, she barred federal prosecutors from seeking the death penalty against an alleged gang leader charged in several Newark slayings, ruling the man's intellectual disability made him ineligible for capital punishment. Salas later sentenced the man to 45 years in prison.
The investigation is being led by the FBI, with assistance from the New Jersey State Police, North Brunswick Police, and the Middlesex County Prosecutor's Office.
The FBI released a statement Sunday night saying, "The FBI is investigating a shooting that occurred at the home of Judge Esther Salas in North Brunswick Township, New Jersey earlier this evening, July 19. We are looking for one subject and ask that anyone who thinks they may have relevant information please call FBI Newark at 973-792-3001. We are working closely with our state and local partners and will provide additional updates when available."
Judge Salas has received threats in the past, sources say, and she is now receiving 24-hour protection from the US Marshals.
"Judge Salas and her family are in our thoughts at this time as they cope with this senseless act," Murphy said in an earlier statement. "This tragedy is our latest reminder that gun violence remains a crisis in our country and that our work to make every community safer isn't done."
Catholic University tweeted their condolences and announced a special mass in Dan Anderl's honor.
Dear Members of the University Community,— Catholic University President (@CatholicPres) July 20, 2020
I was shocked last night to hear news of Daniel Anderl’s tragic death Sunday evening in New Jersey. Daniel was a rising junior, enrolled for classes beginning in the next few weeks. He turned 20 last week.https://t.co/NtEfxrGoxl
St. Joseph's Preparatory School in Metuchen released a statement on former student Dan Anderl's death.
"It is with the utmost sadness that we inform you that Dan Anderl '18 was taken from us last night," it read. "Dan was a true friend, a proud Falcon, and an overall wonderful human being. He will be truly missed. We pray for Dan's family and friends during this unbelievably difficult time -- please know, we are mourning with you."
The Associated Press contributed to this report.