Update on The only American ever executed in Northern Ireland

Back in 2010 I posted about an Eddie Cullens who was an American citizen, hanged for murder in Northern Ireland in 1932. I quickly was able to learn some additional information but never posted it here:

According to his US Naturalization petition (1927) his birth name was Isaac Joseph Cohen born 4 Feb 1903 in Smyrna. He emigrated to the US from Marseilles on the SS Roma on 20 Jan 1920, arriving in New York on 3 Feb 1920.

I found the ships record at ellisisland.org for free: His name was spelled Jsaac Cohen and he was going to his brother Joshua J Cohen who lived on Broadway, his sister Esther Cohen remained in Constantinople. The date and name of ship was the same as on his Naturalization Petition. The brother's name was (mis)spelled Joshna.

So then the challenge came to find any descendants of his brother Joshua, here is some of what I learned:
According to Joshua Cohen' WWI draft registration card, he worked at the 229 E. Bway address but lived at 104 Essex? He was born June 15, 1890 in Smyrna.
I found Joshua and his family in the 1920 census, but couldn't find them in the 1930, or Joshua alone in 1910, or Eddie in 1920 or 1930. On his Naturalization petition, Joshua gave the name, date, and ship of his arrival:
ship Berlin, 18 Jan (possibly June) 1910 arrived in NY.
At elliisland.org, the ship Berlin is shown as arriving on 18 Jan 1910 (and not at all in June) but I checked the whole list a almost all the passengers were Italian.
I did find him in the ship record, in the index his name is transcribed as Tussesa Cohen, but there is an ink blot over his first name and it could be anything. He was travelling with several other people from Turkey but none named Cohen as far as I can tell. He is on line 28 and listed no contact in Turkey, and in New York, "friend Benjamin Cohen 31[?] St. Mark's Place New York"

I had a look at the 1910 census, and either found Benjamin alone, or didn't find any Cohens at the address, I forget which. But it looks like Eddie/Isaac didn't have any close family in NY other than Joshua.

Also on his Nat Pet. Joshua said he was born 15 May 1890 in Smyrna, Turkey
his wife is Louisa born in Bulgaria on 16 Jun (or Jan). He has one child Margaret Cohen born on July 24, 1912.

On his "Declaration of Intent" from 1910 (on the same .jpg file as the Nat Pet), Joshua gives his occupation as Interpreter.

On his draft card from 1917, Joshua's birthday is again given as 15 May 1890, and is a Clerk at the Hebrew Immigrant Aid Society at 229 East Broadway (the organization still exists but the building is being torn down: http://www.boweryboogie.com/2010/01/demolition-of-225-east-broadway-underway.html)

----The whole point of the above is to show that the attached 1920 census return is really Joshua, even though there are some misspellings, and they list him as being born in Russia. On the 1920 census, Louisa and Margaret are listed, and so is daughter Edith, age 1 year  6? months.

We contacted the HIAS where Joshua worked, they were helpful, but they couldn't find much more than. They found the death certificate for Joshua's wife, but no record of next of kin, etc.
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So that's where we left it back in 2010. Perhaps there is something more to learn now that the 1940 census is available. It is such an interesting story.