Originally published July 18, 2011 at 11:31 a.m., updated July 19, 2011 at 6:53 a.m.
The death of veteran Detective Donna Williams and her daughter have been "devastating", police officials said as they investigate the circumstances that led to their deaths.
Williams, 52, and her daughter Briana, 18, were found stabbed to death in their Rancho Peñasquitos home early Monday morning. The victim's son, Kevin Williams, 24, is in police custody and is expected to be charged with murder.
The slayings had a "big impact on everybody in the department", particularly those who worked with Williams, Capt. Jim Collins told reporters.
"We are a family, and a case like this is devastating,'' he said.
The motive for the attack was unclear.
Police were called to the house at 1:22 a.m. and found Kevin Williams sitting near the body of his sister, who appeared to have been pushed out a second story balcony. He was arrested without incident, police said.
Preliminary evidence and interviews "only revealed there was a disturbance between the son, mother and daughter,'' Lt. Ernie Herbert said.
The murder weapon was believed to be a kitchen knife, according to police.
Late last month, officers went to the Williams family home on a call of a disturbance involving the son, said police officials, who declined to provide details about that incident. No one was arrested.
Donna Williams spent 31 years with San Diego police, much of it in the Child Abuse Unit, Collins said outside downtown police headquarters, where flags were flying at half-staff. The detective -- whose late husband, Howard Williams, was also a San Diego police officer -- was a "cornerstone'' of her division, Collins said.
Briana Williams recently graduated from Mount Carmel High School, where she was a standout softball player, and planned to attend a San Francisco design college on a full scholarship, Collins said.
All three lived in the home.