Incognito, starting offensive guard, has been suspended in relation to Jonathan Martin's recent absence from the team related to alleged bullying.
Incognito had been investigated for harassment of Martin, who left the team for emotional treatment last week after a lunchroom incident in which teammates reportedly got up and left a table as soon as Martin sat down.
Martin's representatives say that he has received "racially charged" threats and messages from Incognito in voicemails and text messages. Martin's camp has submitted copies of the messages to the team as evidence of Incognito's intimidation.
Incognito also allegedly got Martin to give $15,000 to help finance a trip to Las Vegas for a group of teammates, even though Martin wasn't joining them. He says he gave the money fearing the consequences he would face if he didn't.
Incognito was voted second-dirtiest player in the NFL from a player poll during the 2012 season. He has racked up penalties throughout his career for verbal altercations with coaches and teammates.
The NFL will conduct a "thorough review" to determine the extent of Incognito's alleged harassment and, if applicable, choose an appropriate punishment.
Incognito took to Twitter on Sunday to defend himself against the allegations.
It is unknown if and when Martin plans to return to the team. The Dolphins have until Tuesday afternoon to take him off the non-football-related illness list.