Wow, what a story. On the Lafayette & Louisville site there is this entry "ORVIS, UnknownND [No Date]SUG [Sugarloaf].
Central City is in Gilpin County ; try their board and someone may have information. I would think in a case like that there would have been a trial or at the least a coroners inquest ; probably in Gilpin County.
I was going to ask who raised them and where but I just noticed that the girls were married (double ceremony) at the "home of the brides' father". That cemetery entry is curious ; I have examples where no stone was set but "Unknown" makes me wonder.
1.Birth - "Williams, Mr & Mrs. G.W. - dau b 18 Apr 1883 South Boulder Canyon. Dr. Bartlett delivered. (HW 25 Apr 1883:5) [HW=Boulder County Weekly Herald]
2.Multiple (under one entry)- "Orvis, Harrison F. G. & Susan - son Ellis Harrison b 30 Nov 1875 western [sic] Sugar Loaf, (CN 10 Dec 1875:2; 1880 census) Son Ellis H. d 5 Jan 1876 West Sugar Loaf. Age 5 weeks 1 day. (CN 14 Jan 1876:2) Dau Zurah b 7 Apr 1877 Sugar Loaf District. (CN 13 Apr 1877:2) Son Orin L. b 18 May 1879 Gordon Gulch. (NAC 30 May 1879:2) [CN=Boulder County News ; NAC=Boulder News and Courier ; "1880 census"=Mrs McRoberts frequently adds information from other sources]
3.Birth - "Jones, Hiram R. & Louella M. - dau b 15 Apr 1881 South Sugar Loaf. (NAC 25 Apr 1881:3; HW 20 Apr 1881:5)
4.Multiple - "Williams George W. & Ida M, Orvis...son Isaac C. b Sugar Loaf. 18 3/4 lbs. (10 Mar 1893:4 US [sic] Living Sugar Loaf June 1900 with ch Laura, Geo, Ida, Millie, Isaac, Florence & Bessie. (US) [US=1900 Boulder County, Colorado census]
5.Multiple [No proof this is your H.R. Jones ; but maybe one of the surnames will ring a bell] - "Plumb, S.J....son Roy & dau Mae & Roy's niece little Gertrude Ash & H.R.Jones visited Mrs. Fisher. (7 Oct 1891:1)S.J.'s sis whom he hasn't seen in 26 years, Mrs. Maxom is visiting from Rowley, Ia. - Canfield. (11 Aug 02)Dying at home N of Erie. 'Well known & highly respected pioneer & former commissioner of this water district.' (25 Dec 93:1)D at home 24 Dec. A dau Nettie is expected from NY & another dau is living at Monrose has been notified. Weld & Boulder Co residents will miss him. (26 Dec 93:4)Funeral from Pleasant View Church near home in Weld Co, today. Attended by several from both counties. (28 Dec 93:1)Neyyie Plum [sic] of Erie & her sis Mrs. Ash & little dau of Montrose, Co visited Marshall Joe Bailey, a good friend of father's. (9 Mar 1894:40Roy is over from Longmont in Boulder looking for a job. (3 Feb 1898:4)
6. "Orvis, Mr....& fam have moved to Loveland. (13 Aug 1892:4)" [who ?]
Didn't see any cemetery listing for these Jones' and no article past the 1881 birth ; makes me think they moved.