Study that shows that homeless people have much higher suicide rates than other groups.
Jack Tsai and Xing Cao, "Association between suicide attempts and homelessness in a population-based sample of US veterans and non-veterans," Journal of Epidemiology Community Health 73, no. 4 (2019): 346-352
US veterans with homeless histories were 7.8 times more likely to have attempted suicide than veterans with no homeless histories (24.5% vs 2.8%). Non-veterans with homeless histories were 4.1 times more likely to have attempted suicide than those with no homeless histories (23.1% vs 4.5%). Lifetime homelessness was independently associated with lifetime suicide attempts in veterans (AOR=3.75, 95% CI 3.72to 3.77) and non-veterans (AOR=1.83, 95% CI 1.83 to 1.84).