[bonanova]

A building has 16 rooms, as shown; each room is occupied by a living person.

There is a door between all rooms with a common wall: you can move to a N S E or W [only] adjoining room.

The room in the northeast corner has the only door that exits the building.

There is no basement, no attic, no tunnel, no roof exit, no secret passageway.

+---+---+---+---+

| p | p | p | p  [b][color="#8B0000"]-> the only building exit[/color][/b]

+- -+- -+- -+- -+

| p | p | p | p |

+- -+- -+- -+- -+

| p | p | p | p |

+- -+- -+- -+- -+

| [b][color="#8B0000"]K[/color][/b] | p | p | p |

+---+---+---+---+[/codebox]
The person in the southwest corner is a killer. None of the other persons is a killer.

If the Killer enters a room occupied by a living person, he immediately kills that person .  

The killer will not enter a room occupied by a dead person.  Curiously, he finds the sight of blood distasteful.


A neighbor hears screams and calls 911.

The police arrive and find a dead body in each of the 15 rooms marked "p".

The Killer was not found.


How did the killer manage to escape? Trace the path he took through the rooms.

[roolstar]

+---+---+---+---+

| p | p | p | p  [b][color="#8B0000"]-> the only building exit[/color][/b]

+- -+- -+- -+- -+

| p | p | p | p |

+- -+- -+- -+- -+

| p | p | p | p |

+- -+- -+- -+- -+

| [b][color="#8B0000"]K[/color][/b] | p | p | p |

+---+---+---+---+[/codebox]

[spoiler=Here we go]

[codebox]+---+---+---+---+
| 11| 12| 13| 16 [b][color="#8B0000"]-> the only building exit[/color][/b]
+- -+- -+- -+- -+
| 10| 9 | 14| 15|
+- -+- -+- -+- -+
| 1 | 8 | 7 | 6 |
+- -+- -+- -+- -+
| 2 | 3 | 4 | 5 |
+---+---+---+---+

The trick is to out of the bottom left corner, kill one person, then come back in the EMPTY corner room then move out to the second adjacent room again!!

Nice one!

[bonanova]

Nice job!

If you color the rooms like a checkerboard you find that the SW and NE squares have the same color.

If you touch every square, you can't start and finish on the same color.

So you go to a square of a different color to start from.

Then come back immediately to the SW corner -- otherwise you'll encounter dead bodies.