Does the newspaper it cites actually state, "...done to death..."?
Yes, the article published in The Guardian Friday 20 September 1935, page 13 under the heading: "Nazi Concentration Camps Not Improved" uses the expression "done to death" twice with regard to Dachau, including in the very last sentence: "The total number of prisoners known to have been done to death in Dachau is 44."
The article notes that the deaths, which happened between 12 April 1933 and 22 May 1935, included 15 who they list as being Jewish.
As a side point - I note that the article also states that Dachau holds around 1,600 prisoners, explaining that: "The Jews include thirty who returned to Germany this year, thinking it to be safe, and were sent to Dachau."
It is the above article that is referred to in The Golden Age 8 April 1936 which featured articles regarding the situation in Germany over the first 14 pages of the magazine.