try
http://www.castlegarden.org/ this vip website needs donations
their passenger lists should reduce your hunt to one of these Margaret Purcell
I selected 1860-1899 arrival times. if you go through each one looking at the detail most are irish but please do search for Kilkenny or occupation public house worker quess etc.
Margaret Purcell 33 F 10 May 1860
Margaret Purcell 19 F 15 Jun 1860
Margaret Purcell 40 F 20 Dec 1860
Margaret Purcell 18 F 14 Jul 1862
Margaret Purcell 20 F 9 Sep 1862
Margaret Purcell 25 F 9 Sep 1862
Margaret Purcell 45 F 23 Dec 1862
Margaret Purcell 40 F 22 Jun 1863
Margaret Purcell 28 F 10 Aug 1863
Margaret Purcell 29 F 11 Mar 1864
Margaret Purcell 22 F 20 Jan 1865
Margaret Purcell 18 F 5 May 1865
Margaret Purcell 20 F 5 May 1865
Margaret Purcell 22 F 5 May 1865
Margaret Purcell 27 F 5 Aug 1865
Margaret Purcell 19 F 12 Sep 1866
Margaret Purcell 26 F 6 Apr 1869
Margaret Purcell 30 F 4 Jun 1867
Margaret Purcell 38 F 16 Jul 1867
Margaret Purcell 21 F 3 Jul 1868
Margaret Purcell 26 F 7 Sep 1868
Margaret Purcell 21 F 29 Jul 1870
Margaret Purcell 22 F 10 May 1871
Margaret Purcell 18 F 27 Apr 1872
Margaret Purcell 16 F 7 Jul 1873
Margaret Purcell 2 F 21 May 1874
Margaret Purcell 26 F 2 Jul 1874
Margaret Purcell 26 F 14 Apr 1880
Margaret Purcell 4 F 11 May 1881
Margaret Purcell 23 F 21 Sep 1883
Margaret Purcell 29 F 21 Feb 1884
Margaret Purcell 18 F 18 Apr 1885 TIPPERARY
Margaret Purcell 43 F 22 Apr 1885
MARGARET Purcell 18 F 23 Sep 1893 IRELAND
The murder in a pub might have been reported in an irish newspaper but which one and are they
all indexed in these two collections
index 1
https://www.irishnewsarchive.com index 2
British Newspaper Archive Colindale londonthe latter includes the Kilkenny Journal, and Leinster Commercial and Literary Advertiser Kilkenny, Republic of Ireland I quickly searched both without success covering 1860-1899
She should be listed in her maiden name in US census have you tried them all.
That’s all I can offer