Aubrey Trail, a 52-year-old from Nebraska, yelled “Bailey is innocent, and I curse you all” before swiping something across his neck.
Deputies rushed to help Mr Trail as he lay bleeding on the floor.
Mr Trail was referring to his 25-year-old former roommate Bailey Boswell when he cut himself. The two have been charged with first-degree murder in the killing and dismemberment of 24-year-old Sydney Loofe.
It was unclear how badly Mr Trail was injured during the incident. The judge presiding over the case ordered the jury to return on Tuesday morning.
Authorities said Mr Trail has suffered declining health while in custody. He reportedly had a stroke and two heart attacks since his arrest.
Ms Loofe went missing in November 2017 after going on a date with Mr Boswell, who she reportedly met on the dating app Tinder. Mr Trail was Mr Boswell’s roommate at the time of the alleged murder.
Prosecutors have said the two men planned Ms Loofe’s abduction and killing.
Mr Trail’s attorneys have argued her death was the result of an accident that occurred during a consensual sex fantasy.
Mr Boswell is still awaiting trial.
Additional reporting by AP