A California fertility doctor was charged with murder Friday in the November 13, 2016, killing of his wife, a report said.

Eric Scott Sills, 54, was arrested Thursday in connection to the death of 45-year-old Susann Stephanie Arsuaga Sills, the Orange County Register reported, citing jail records. Sills is held on $1 million bail.

Several details regarding the case remained unclear, including the woman’s cause of death, a motive for the murder and what led to the doctor’s arrest last week.

Sills is medical director at the Center for Advanced Genetics fertility clinic in Carlsbad, the Register reported. His wife was the center’s managing partner and co-founder. They were the parents of twins.

Sills, who holds a doctorate from London’s University of Westminster and a medical degree from the University of Tennessee, practiced in-vitro fertilization in Europe and the U.S. and wrote books on the topic, according to an online biography. He was also part of a team that discovered three previously unknown human gene mutations.

Sills is a 1983 Harriman High School graduate and a 1985 Roane State Community College graduate; he later attended Vanderbilt University and graduated in 1987 before attending the University of Tennessee Medical School at Memphis.

Information courtesy Brad Jones/BBBTv