Any such agreement would have to be approved by the court, and Arbery's parents would most likely have influence. Prosecutors did not reveal details of the plan, but only served notice that a deal was ready for the U.S. District Court in Brunswick, Georgia, to hear.
The Sunday filings name son Travis McMichael and father Gregory McMichael. The third convicted murderer in the case, neighbor William "Roddie" Bryan, was not mentioned.
In early January, Arbery's parents refused to endorse a proposed deal for the McMichaels to serve 30 years each if they admitted they were motivated by hate.
In a statement Sunday night, Arbery's parents, Wanda Cooper Jones and Marcus Arbery, said they are "vehemently against" the plea deal because it would allow the McMichaels to serve time for both cases in a "preferred" federal prison.
"This proposed plea is a huge accommodation to the men who hunted down and murdered Ahmaud Arbery," the parents said in a statement to NBC News.
Arbery, 25, who was Black, was fatally shot Feb. 23, 2020, while jogging outside Brunswick, Georgia, after being followed by the McMichaels, who are white, in a pickup truck. Their neighbor, Bryan, also white, joined in the pursuit and captured key moments on video.
The father and son said they believed Arbery was a burglar. Travis McMichaels said Arbery was trying to take his shotgun when he shot him twice.
All three men were found guilty Nov. 24. The McMichaels were sentenced this month to life in prison without the possibility of parole; Bryan's sentence includes the possibility of parole after 30 years' incarceration.
In April, a federal grand jury indicted the three in a hate crime case that included charges of interfering with the victim's rights and attempted kidnapping.
The McMichaels were also charged with using, carrying and brandishing firearms (Gregory took out a handgun during the confrontation), and Travis faced an additional charge of opening fire during a crime of violence.