Research Question Does prior information retained in police intelligence records about an offender's suicidal tendencies help to predict a future domestic homicide or attempted homicide? Data Records on 158,379 arrestees in 1997-2015 were examined for suicidal or selfharm warnings by date of entry and compared to 620 offenders identified in cases of domestic homicides or serious violence over the same time period. Methods The percentage of offenders in domestic homicide and serious violence cases who were known to have reported suicidal ideation prior to those crimes was compared to the overall percentage of arrested persons who had such reports. Findings Of the total 620 deadly violence offenders, 125 had a marker for suicide or self-harm, of which 35 (5.6%) were posted prior to the deadly domestic violence. Of the 80 homicide cases (excluding grievous bodily harm), 7 had suicide or self-harm markers prior to the homicidal offence, for a rate of 8.75%. These rates compare to an overall marker rate among the 158,379 arrestees in the time period studied, of whom 7,241 were identified as holding a warning marker at the point of data collection for this study in 2016, which equated to only 5% of the group, of which an estimated 38% would have occurred prior to a crime (2,752 cases), or 1.7% of the 158,379. By that metric, it is three times more likely that offenders charged with an act of deadly domestic violence had prior suicidal warning markers than offenders not charged with DOI 10.1007/s41887-017-0009-8 Published online: 2017 31 July such crimes (5.6/1.7 = 3.3), and 5.2 times more likely for homicide offenders to have a prior marker than for all arrestees. Conclusions Police intelligence system markers for suicide or self-harm can provide valuable information for building more accurate prediction models for domestic homicide and serious assaults.