But the pic at #198 gives a pretty good view of the garage roof and there is no projection there to account for the headroom of a stairway. Notice the division of floors on the house. The one between basement and 2nd floor is about midway up the garage wall. There could be no straight pass-thru door between garage and house. The floor levels don't match. No door on the back wall that we can see either.
I think it's near certain that the only way in and out of that garage is the big door. Since we're working from pics that don't reveal all walls of the garage I'll give it a 99.9% certainty.
The street level Google earth pictures of this property may give more detail: http://maps.google.com/maps?q=800+a+street+se+washington+dc&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&hq=&hnear=800+A+St+SE,+Washington+D.C.,+DC+20003&gl=us&ei=ipFUTcGiEMXZgQfrhLXiCA&sa=X&oi=geocode_result&ct=title&resnum=1&ved=0CBMQ8gEwAA
The one from above shows their second car parked diagonally so that one would have to leave the garage at an angle..