Multiple sources confirmed to ESPN that the following is a transcript of a voice message Incognito left for Martin in April 2013, a year after Martin was drafted:
"Hey, wassup, you half n----- piece of s---. I saw you on Twitter, you been training 10 weeks. [I want to] s--- in your f---ing mouth. [I'm going to] slap your f---ing mouth. [I'm going to] slap your real mother across the face [laughter]. F--- you, you're still a rookie. I'll kill you."
Sources tell ESPN NFL Insider Adam Schefter that officials from both the NFL and the Dolphins have heard the tape and have copies of the message.
Sources familiar with the tapes say these are terms Incognito used over time and were not isolated incidents, including the use of the racial epithet multiple times.
Sources also say Martin received a series of texts that included derogatory terms referring to the female anatomy and sexual orientation.
Incognito was suspended indefinitely by the Dolphins on Sunday night for conduct detrimental to the team. Meanwhile, the Miami Herald reported Monday that the team plans to cut ties with him.
"He's done," a team source told the newspaper. "There are procedures in place, and everyone wants to be fair. The NFL is involved. But from a club perspective he'll never play another game here."
In a statement announcing his suspension, the Dolphins said, "we believe in maintaining a culture of respect for one another and as a result we believe this decision is in the best interest of the organization at this time. As we noted earlier, we reached out to the NFL to conduct an objective and thorough review. We will continue to work with the league on this matter."
Incognito, who had been a part of Miami's six-player leadership council, started all eight games for the Dolphins (4-4). He will be an unrestricted free agent after the season. Backup guard Nate Garner will start in his place.
Martin left the team last week after a lunchroom incident. It is unknown whether and when Martin plans to return to the team.
Martin also missed two days of organized team activities this past spring, and the team knew he was struggling and unhappy without knowing the exact reason why, league sources told Schefter. Martin did not identify Incognito as the source of his unhappiness out of fear of retribution and not wanting to roll over on his teammates, according to league sources.
The Dolphins have until 4 p.m. ET Tuesday to take him off the non-football-related illness list.
This is not the first time Incognito has been in trouble. In 2009 he got into a verbal altercation with then-St. Louis Rams coach Steve Spagnuolo for multiple penalties in a game. Incognito was waived a few days later. Incognito also was suspended for the 2004 season in college at Nebraska because of off-the-field incidents.
On Monday, Smith said he wasn't surprised Incognito was involved in such an incident.
"You are what you are I guess," Smith said. "That doesn't surprise me one bit."
"I would just say he's a jokester kind of guy," Garrard said. "A good guy, but like all of us, you want to have your fair shake of pranks and stuff like that. ... It's unfortunate. You never want it to get to a point where guys want to leave the team. You would hope other guys in the locker room would help police it. It's one of those situations that's sad to see."
"He needs to be gone," Scott said. "No one would miss him anyway. Trust me."
Scott added: "You got to be some type of loser in your spare time away from the building you want to call me and leave threatening messages and text messages on my phone. That's taking bullying to a whole other level."
Scott himself is no stranger to rookie hazing, as he was seen on the Jets' season of "Hard Knocks" as part of a group of veterans tying a rookie player to a goalpost and dousing him in ice, Gatorade and powder.
Incognito talked to NFL.com this past summer about problems he's had to overcome through therapy with anger-management issues and substance abuse, particularly when he was with the Rams at the beginning of his career.
"I mean, we'd have practice the next morning, and I'm out until all hours of the night, running the town," Incognito told NFL.com. "Drinking. Doing drugs. I was doing everything that a professional athlete should not be doing."
He had seemed to turn his image around with the Dolphins, however, earning a share last season of the team's "good guy" award, which is given to the player who is most cooperative with the local media. He also was voted to his first Pro Bowl in 2012.
"I'm definitely not a choir boy," Incognito told NFL.com in the story published earlier this year. "You know, I'm definitely not healed, and I'm not saying that I don't make mistakes. But from where I was to where I am now, I mean, it's night and day. And it's something that, you know, I hope people can respect about me."
ESPN.com Dolphins reporter James Walker, ESPN.com Texans reporter Tania Ganguli and ESPN.com Jets reporter Rich Cimini contributed to this report.