Attempted Murder of a Young Child Followed by an Attempted Suicide of the Mother by Injection of Insulin Aspart: Identification of Quantification of Insulin by LC–HRMS and UPLC–MS/MS in Blood of the Two Cases

Abstract

Abstract The identification and quantification of insulin and its analogs have always been a challenge in the forensic field. Murder, suicide attempts and induced hypoglycemia in the context of factitious disorders have been described with the use of synthetic analogs of human insulin. There is very less information in the literature about aspart insulin concentrations in overdose cases. In this paper, we present a case of a nurse who tried to murder her 10-year-old daughter by injecting her aspart insulin and who, later, tried to commit suicide by injecting herself the same hormone. Two empty syringes and a FIASP® Flextouch pen were found in the woman’s apartment. A liquid chromatography coupled to high resolution mass spectrometry (LC–HRMS) method was developed in order to identify and discriminate aspart insulin from human insulin in blood samples as well as in syringes and pen, while an liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) method was developed for the quantification of insulin in blood samples. Aspart insulin tested positive at 5.7 and 2.4 ng/mL in the blood specimens of the mother and the child, respectively. The substance contained in the syringes and pen also corresponded to aspart insulin. Although the mother claims to have injected an overdose of aspart insulin, the concentrations found were in the therapeutic range for subjects under therapy. Due to the high instability of insulin and the long time elapsed between sampling and forensic analysis (8 months) due to administrative reasons, the concentration at the time of collection was probably much higher. In this case, it was possible to identify aspart insulin and discriminate it from human insulin in a context of attempted murder and subsequent attempted suicide using high-resolution mass spectrometry, which is of paramount importance in forensic medicine.