I am not sure where the "olly olly" comes from, but in both instances you gave, this is the meaning.
In childrens' games, it means something more akin to "I didn't get caught!" (as I'm sure you know)
Hope this helps.

I believe that it is based on the old English phrase "all ye" meaning all of you or everybody. Olly would be the phonetic way of writing of all ye. It is said at the end of a game of hide-and-seek. All those who haven't been found and tagged get to come in without penalty.

In your sentence, it means that the person hopes to get out of the penalty for committing murder by claiming a point of law. But in Gitmo, that particular point of law will not make someone safe from prosecution for murder.

all ye all ye in come free....
remember that as a child? We used it in relivio, a hiding game of out foxing the opposite team.
http://forums.opendemocracy.net/node/29847

All ye, all ye, in come free!
About 6 o'clock nearly most every night in the few good weather months we enjoyed in Orono, Maine, the neighborhood children would gather next door at Dottie Boothby's house to play our nightly game of "Hide and Go Seek". Back in the mid-fifties, we all had had our suppers, and we generally played until it got dark, or, until it was bedtime...
I'm sure you all know how the game is played – I have seen children play this game everywhere I have been – Egypt, Nicaragua, Maine, Greater Boston – as far as I know it is a universal game for all children. One person is "it" and he or she closes their eyes and starts counting. All the others go and hide while the counting goes on...
There was one last rule that took effect when the person who was "it" had had enough. And the rule was when the person who was "it" gave up, ***they would yell "All ye, all ye, in come free!" And everyone who was hiding could come in and would not be regarded as being "caught" or "found".***
http://www.saintlukesmethodist.org/sermons/archives/all_ye_a...

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Note added at 1 day1 hr (2008-11-07 17:19:15 GMT)
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In my childhood, the phrase [Ollie ollie oxen free] was heard and said as "All ye, all ye, in come, free!" This was in a mid-sized, New England city with a large population of Irish origin, which is surely why the "ye" made sense. "In come, free" was, of course, the acknowledgment of defeat on the part of "It."
http://www.takeourword.com/Issue089.html

Anyhow, my point is that "oxen free" survived, for all children know what an oxen is (in farming communities), but not what "All ye" is... as this form of English has expired. Since children taught children this game, not adults, I can see the phrase slowly becoming warped.. after all, there is a complete turn over of children every 5-10 years in this game. Ollie = All ye.
http://en.wikipedia.org/wiki/Talk:Hide_and_seek

Ollie Ollie In Come Free - has nothing to do with politics, income, Oliver North, etc., though you can read politics into anything I suppose. It was shouted at the end of a kids' hide and seek game, and probably started around the turn of the 20th Century, because of its mix of German/English, etc. Lots and lots of theories from lots and lots of sites. Most from Jesse at Random House: 1. The phrase is used in a variety of children's chasing games, especially hide-and-(go-)seek. The rough form of this game is that a player (called "it") gives other players a chance to hide, and then tries to find them. When "it" finds the first hider, he calls out some phrase indicating that the other players are "safe" to return "home," at which point the person "it" found will succeed him as "it." The original form of the phrase was something like all in free or all's out come in free, both standing for something like all who are out can come in free. These phrases got modified to all-ee all-ee (all) in free or all-ee all-ee out(s) in free; the -ee is added, and the all is repeated, for audibility and rhythm. From here the number of variants takes off, and we start seeing folk etymologies in various forms. The most common of these has oxen replacing out(s) in, giving all-ee all-ee oxen free; with the all-ee reinterpreted as the name Ollie, we arrive at your phrase, which, according to the Dictionary of American Regional English, is especially common in California. Norwegian settlement areas have Ole Ole Olsen's free. For the out(s) in phrase, we also see ocean, oxford, ax in, awk in, and even oops all in. 2. One guess is that the original was something like "all in free" for "all who are out can come in free", to indicate that the person who is "it" in the game of hide-and-seek has caught somebody to become the new "it", and so everybody else can come out of hiding without the risk of being caught. Oral transmission has garbled this in fascinating ways, with all in, for example, being translated by a series of mishearings to the name Ollie (short for Oliver, once more common than it is now). And oxen may have come from an intermediate form out's in free - other recorded versions are awk in, Oxford, and ocean. Various subscribers remember versions that suggest the first part of the catch was once something like "all of you". Charles Wilson wrote: "When I was growing up in the American South we actually said, 'All ye all ye outs in free' when playing hide-and-seek (although we called it 'hide-and-go-seek)". 3. Its root seems to be an English-Norman French-Dutch/German concoction: "Alles, Alles, in kommen frei"or "Oyez, oyez, in kommen frei!" "Allez, allez" was a Norman addition to the English language, pronounced "ollie, ollie" and sometimes written "oyez, oyez" and meaning "everyone." "In kommen frei" was a phrase popular in Dutch/German New York and Pennsylvania, where many Zonians came from, meaning "come in free."
http://www.songfacts.com/detail.php?id=1736&