There's an interesting article that was published in the Berkley Gazette about Ingrid in 1973.
Colby, Norman "Our Missing People: Ingrid Anderson",
The Berkeley Gazette (Berkeley, CA), Jan 2, 1973, pg 1-2.
Ingrid Anderson (1) - Newspapers.com™
Ingrid Anderson (2) - Newspapers.com™
"Ingrid Anderson left [her] Richmond home that morning headed for a barber shop...it was the last time the 27 year old housewife has been seen or heard by her family"
"Her husband was Steve Anderson, a Richmond police officer until his resignation from the force several months ago." After Ingrid went missing he moved out of state with the kids and remarried.
Her nickname was Ronnie (or Roni), but she reportedly "was not satisfied with her real name, in high school, she sometimes went by the name Judy or other names"
"She spent hours enhancing her blue eyes and olive skin with the right makeup, and occasionally had her brown hair darkened, or else worse one of several wigs in her wardrobe." The article goes on to mention that she was obsessed with dieting to the point it was detrimental to her health.
"Ronnie [Ingrid] graduated from Richmond High in 1962 and became a student at Contra Costa College."
Her mother, who lived in Castro Valley, was the one to report her missing instead of her husband. Her kids were 1 and 4 when she went missing.
"investigators found no notes [to suggest where Ingrid had gone]."
"Her mother gave her a car in high school and she was never without wheels after that. She would not go around the block without the car. Ronnie's car was parked in front of her home when left. The car itself yielded no clues."
This was published by her mother in the San Francisco Examiner in 1986:
The San Francisco Examiner, Jan 7, 1986, pg 18. https://www.newspapers.com/article/the-san-francisco-examiner-ingrid-anders/133732608/
"To Ingrid Roni Routt,
When you left, I felt sadness, even strangers felt my grief. I cried and cried, until I didn't have any tears...I pray to go that we will be together again. Please remember me. I love you dearly. You have been a previous gift to me from God. Miss you terribly, MAMA. HAPPY BIRTHDAY DARLING."