Silvia Lange, 77, of Nicasio, California, was last seen January 23, 2010, at Point Reyes National Seashore. An experienced hiker, she went to the North Beach area to walk her dog Hettie. Hettie was found alone near a parking lot that evening and rangers located Lange’s vehicle with her two other dogs, Neria and Sika, inside.

Lange was 5 feet tall, about 145 pounds, with brown hair and brown eyes. She was reported wearing a red raincoat, a white down jacket, and dark pants. Described as active and in excellent health, she was a former psychiatric nurse, college instructor and mental health author who volunteered training service dogs and supporting several local organizations.

About 50 people, three dog teams and a mounted patrol took part in an extensive search but no trace of her was found. Authorities’ prevailing theory is that she may have fallen while walking Hettie and been swept into the ocean by a sneaker wave; a friend suggested Hettie could have pulled on the leash and caused a fall. Her body has never been recovered.

If anyone was in the North Beach area that day or has information about Lange’s movements on January 23, 2010, please come forward.