SAN QUENTIN (CBS) — Condemned killer Orlando Romero, sentenced to death along with his brother Christopher Self in 1996, died Sunday at a hospital outside of San Quentin while being treated for a COVID-19 infection, according to state prison officials.

Romero is the 11th death row inmate to die while being treated for COVID-19 since the virus outbreak swept through San Quentin beginning in June. The last execution at San Quentin was in 2006.

Prison officials said Romero’s death appears to be from complications related to COVID-19, but a coroner will determine his exact cause of death.