His blood was shed in vain, like the wind's path. ذَهَبَ دَمُهُ دَرَجَ الرِّيَاحِ‏.‏

His blood was shed in vain, like the wind's path.
It is also said, "like the wind's path," which is the plural of "path," meaning its way. This proverb is used to describe blood that is shed in vain, with no one to seek retribution.
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The proverb “His blood went unavenged” is used to describe a right or blood that was lost in vain, with no one seeking retribution or demanding justice.
Some of the closest English equivalents are:
“His death went unavenged.”
Meaning: His death occurred without vengeance or retribution.
This is very close in meaning to the proverb.
“His blood was shed in vain.”
Meaning: His blood was shed in vain.
One of the most common and closest equivalents.
“Justice was never served.”
Meaning: Justice was not served.
“His case fell through the cracks.”
Meaning: His case was lost and neglected.
Although this is broader in meaning than blood.
“It was swept away by the wind.”
Meaning: It vanished without a trace, which is close to the original meaning of the proverb.
The closest equivalent to the Arabic proverb is:

“His blood was shed in vain.”
“His blood was shed in vain, and no retribution was sought for him.”
If the focus is on the loss of justice and the absence of anyone demanding it, the closest expression is:
“His death went unavenged.”
“His blood was shed in vain, with no one seeking retribution or vengeance.”
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ويروى ‏"‏أدراج الرياح‏"‏ وهي جمع دَرَج، وهي طريقها‏.‏
يضرب في الدم إذا كان هَدَرا لا طالبَ له‏.‏