Alcohol and drugs are fuelling homicide and suicide rates in Northern Ireland, an independent report said.
The problem is greatest among young people, with mental illness, substance abuse, drink, previous self-harm and deprivation contributing to most cases, the University of Manchester study added.
There were 332 suicides of young people over a nine-year period and last year, the number of suicides reached its highest figure ever.
Research author Professor Louis Appleby said: "In homicide and suicide generally, alcohol misuse was a more common feature in Northern Ireland than in the other UK countries and a broad public health approach, including better dual diagnosis of mental illness and alcohol or drug misuse, health education and alcohol pricing, should be seen as key steps towards reducing the risk of both homicide and suicide.
"In particular, there needs to be a focus on developing new services for young people with substance misuse problems."
The National Confidential Inquiry into Suicide and Homicide by People with Mental Illness was commissioned by the Public Health Agency.
A total of 1,865 suicides occurred in the general population in Northern Ireland between 2000 and 2008, equivalent to 207 per year. This rate is higher than the UK average but lower than that in Scotland. There were 533 suicides in current mental health patients.
According to Health Minister Edwin Poots, there were 313 suicides in Northern Ireland last year. He said the upward trend in the number of deaths has occurred despite strenuous suicide efforts across the statutory, community and voluntary sectors.
Prof Appleby added: "High rates of substance misuse and dependence run through this report and, as we rely on information known to clinicians, our figures are likely to underestimate the problem.
"Alcohol misuse was a factor in 60% of patient suicides and this appears to have become more common during the course of the study period. Alcohol dependence was also the most common clinical diagnosis in patients convicted of homicide, with more than half known to have a problem prior to conviction."