Above 60,000 feet, up to 100,000 feet is an interval of 40,000 feet. A falling object will cover that distance in a vacuum in 50 seconds (16T^2=40,000 therefore t=50), attaining a terminal velocity of 80,000 feet per second. (More than 54,000 miles per hour)
Absurd, of course. But the magnitude of the velocity does allow for the question of whether or not the now trivial speed of 700 miles per hour could be achieved before the thickness of atmosphere intervened.
Compression of the air below the falling object will exert a force varying directly with the rate of descent. The magnitude of that force is also variable with the shape, and density of the object, and the pressure, and temperature of the air. Even at the extreme altitude of 100,000 feet there is some air, and it has some resistance to offer a falling object. The object need fall only six hundred or so feet to break the sound barrier on the surface, if it followed the curve for objects falling in a vacuum. However, the force opposing the acceleration increases at the same geometric rate as the speed, until it becomes equilibrium. As the object falls, it also enters a steeply increasing density of air over distance. However quickly the object reaches its terminal velocity in the low-density medium, it cannot exceed that velocity, and the magnitude of the terminal velocity decreases as the altitude decreases.
I do not have figures for the specific problem, however, the upper atmosphere of the Earth does not drop off in a uniform manner, throughout the world, or at all times in any area. The Tropopause extends upward to 70,000 feet at times, or less, and the abruptness of the demarcation is not constant, either. Finding out the answer for a particular object would require information for the day, time, location, and weather conditions, the size, position in flight, weight, surface materials of clothing, and a huge other list of variables. Hence, I imagine the guarded statement that someone might have gone faster than the speed of sound. I think it unlikely.