new bool:Marker[MAX_PLAYERS];

public OnGameModeInit()
{
    SetTimer("CheckWanted", 2000, true);
    return 1;
}

forward CheckWanted();
public CheckWanted()
{
    for (new i = 0; i < MAX_PLAYERS; i ++)
    {
        if (!IsPlayerConnected(i)) continue;
        if (GetPlayerWantedLevel(i) == 6)
        {
            // The player's color will be set and other players can see it on their radar.
            SetPlayerColor(i, 0xFF0000FF);
            Marker[i] = true;
        }
        else
        { 
            if (Marker[i]) 
            {
                SetPlayerColor(i, 0xFFFFFFAA);
                Marker[i] = false;
            }
        }
    }
    return 1;
}