The first part of this verse is in the form of a chiasmus, or A-B-B′-A′ structure, in which the second line essentially reverses the order of the first. This may be seen in the rendering of Revised Standard Version:
Whoever sheds the blood of man
by man shall his blood be shed;

Furthermore, each line contains the same number of stresses. It is not surprising therefore that many translations place verse 6 in indented lines to call attention to its poetic form. The Hebrew Bible prints verse 6a as two half-lines and verse 6b as two half-lines.

Verse 6 affirms that human life is not to be taken; but if it is, the life of the murderer is to be taken. This verse does not say how that is to be done.

Sheds the blood of man: sheds, a verb meaning to cause to flow, is used frequently in the Old Testament with blood as the object. However, it is also used speaking of tears in Psa 119.136. When used with blood the sense is “to cause death,” “to kill.” Since the causing of death or killing is assumed here to be intentional, Good News Translation renders it “whoever murders a man.” Man is ʾadam with the article and so refers to “anyone,” “a person,” “a human being.” Man in the expression by man again contains the article and so has the same sense as above. Shall … be shed translates the passive of the verb “to shed” used in the first line.

Since man here refers not to any particular man, or even to males exclusively, it may be more suitable to use inclusive language and say, for example, “Human beings were made like God, so whoever murders a person will be killed by someone else.” In languages that do not use the passive, we may say “God made human beings like himself, so somebody will kill the person who murders another human being.”

Even though the text itself does not say how the life of a murderer is to be taken, in some languages and cultures it will not be sufficient to use the indefinite “somebody” as the subject of the verb when it is transformed from the passive. Such a rendering suggests that the murderer will meet his death by chance rather than in accordance with the laws or customs of the human community. It may not be wise to go as far as naming a relative of the murdered person as the one who kills the murderer, even though we know this was the practice among the people of Israel in some periods, and even though it may still be the custom in some cultures today. Generally a term like “the people” can be used, which means that people act together or in accordance with custom. For example, “The person who kills another person, he himself must die at the hands of the people” and “The person who kills another person, the people of his community must kill him….”

The second half of the verse, printed as two half-lines in the Hebrew Bible, does not have the same chiastic structure as the first half, but each half-line appears to have the same number of stresses, and so is poetically bound to verse 6a and often printed in indented lines the same as 6a.

for in the image of God
made he man.

For God made man in his own image: for introduces a clause of reason, making this sentence the reason why human life is not to be taken. Man again means human beings; however, the term has a collective sense in this case: “people” or “human beings [plural].” In his own image is the same as 1.26, 27. See there for comments.

Some languages prefer for stylistic reasons to place the reason before the statement, and so in such cases verse 6b will be placed before verse 6a. See Good News Translation. On the other hand Biblia Dios Habla Hoy translates “If anyone kills a man, another man will kill him, since man was created in God’s likeness.”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .