Brandon Higgs, who was active in private neo-Nazi chat groups, said "Go back to Africa!" before the shooting in a Baltimore suburb.
Cell phone videos appear to show a suspect physically assaulting the women, one of whom is YouTube star Eden the Doll, as bystanders look on.
Gregory and Rachel Howell were caught on camera yelling "white lives matter" and giving a Nazi salute in Torrance, California, last month.
Suspect Eric Breemen told a Sikh store owner from Colorado to "go back to your country," according to an advocacy group.
Video showed two people painting over the mural on Saturday. Racism, said one of them on camera, is a "leftist lie."
Althea Bernstein, who is biracial, was attacked by white men who poured lighter fluid on her and set her on fire earlier this month.
The Oakland Police Department, with help from the FBI, is investigating both displays as possible hate crimes.
The revelation came during a preliminary court hearing for Travis McMichael and his father Gregory McMichael.
Attorneys for Arbery's family said they were confident the "DOJ would do their part to fully investigate all players involved in this murder."
The surge was marked by deadly attacks on Jews in California, New Jersey and New York last year.