Seals, 40, of Lyndhurst, was investigating the death of a livery driver in Bayonne when David Anderson, 47, and Francine Graham, 50, shot him in the Bayview Cemetery just before 12:30 p.m. Dec. 10, and drove off, U.S. Attorney Craig Carpenito said.
They were killed in a gunfight with police, but not after killing three other people.
Based on the arsenal of guns and a viable bomb found in their U-Haul truck, as well as Google searches and more, authorities believe that the couple had been plotting even more bloodshed, Carpenito said.
Seals, however, distracted them during the hateful Dec. 10 attack, the U.S. attorney said.
"By stopping and doing solid police work, we believe [Seals] threw Graham and Anderson off of...a broader plan," Carpenito said during a news conference Monday in Newark. "It probably lead to saving dozens if not more lives."
"This was nothing but a senseless, evil cowardly act of anti-Semitism and hatred toward not only the Jewish community but also law enforcement, Carpenito said. "We know now that they planned even greater acts of mayhem."
After fatally shooting Seals, Anderson and Graham got back in the rented van and drove to JC Kosher supermarket on Martin Luther King Drive.
There, they killed three more innocent victims: store owner Mindel Ferencz, 33; Moshe Deutsch, 24, of Brooklyn; and store employee Miguel Rodriguez, 47.
Five guns were recovered from Anderson and Graham inside the store, including a 12-gauge shotgun carried by Graham and an AR15-style weapon that could have been self-manufactured, and was possibly carried by Anderson, authorities said.
An explosive device found in Anderson and Graham's rented U-Haul had the capacity to kill or hurt people up to 500 yards -- or five football fields -- away, FBI Special Agent In Charge Greg Ehrie said.
A second viable bomb could've also been constructed with all of the material that Anderson and Graham had, Ehrie said.
Authorities recovered at least two handwritten notes from Anderson's pockets, one of which was a reference to the title of a 1990 documentary that describes a member of law enforcement as "fascist pig cops."
Another note had the phone number of a Keyport man who days after the attack was charged with illegally possessing 12 firearms.
A third note found inside the U-Haul read: "I do this because my creator makes me do this and I hate who he hates," authorities said.
Seals approached Anderson and Graham because they were suspected of killing a livery driver the previous weekend in Bayonne.
Click here to follow Daily Voice Fair Lawn-Glen Rock and receive free news updates.