Sketch of the suspect in a series of attacks based on details from a victim of an attack near UCSD.

SAN DIEGO — A woman in Mission Valley was robbed and sexually assaulted in what police believe may be the sixth in a series of home-invasion robberies targeting Asian women.

The woman, 29, was attacked about 11:30 a.m. Tuesday at her home on Reflection Drive off Ambrosia Drive, San Diego Capt. Jim Collins said.

She had just arrived home after shopping with her 18-month-old son and had taken the toddler into her apartment and come back outside to retrieve some belongings, Collins said. As she was going back inside, the man grabbed her from behind and threatened her with a knife.

The man demanded money and then sexually assaulted the woman and left. Collins would not describe the nature of the assault but said she was not raped.

The boy was not injured.

The man was described as white or Latino, about 30 years old, 5 feet 6 inches tall with a medium build. He was wearing a black jacket, jeans and black shoes.

Investigators believe he may be the same man responsible for at least five other attacks since June. The man used a knife, demanded money and in all but one case, he raped, sexually assaulted or threatened to sexually assault the victims.

The first incident was reported June 6 in the College Area on Montezuma Road. The second occurred Nov. 7 at the University of California San Diego's Mesa graduate student housing complex. Both women were raped.

The third case was Jan. 16 in Tierrasanta on Camino Playa de Oro. That woman was confronted in her garage and robbed of cash, Collins said.

The fourth attack happened Feb. 10 in Carmel Valley on Whispering Hills Lane, and the fifth attack was March 4 on Carmel View Road. In those cases, the man entered the homes through open garage doors. The assailant threatened to rape one woman and sexually battered the other.

All the attacks happened between 11 a.m. and 5 p.m. The man either enters through the garage or an unlocked front door, generally when the victim is carrying items into her home, police said.

All the victims were Asian women between the ages of 20 and 48.

The man has been described in each case as white or Latino, in his 20s or 30s, 5 feet 6 inches to 5 feet 9 inches tall, with a thin to medium build.

The victim in the UCSD incident was able to provide a detailed description of the attacker, and campus police released a sketch.

Police advise women to keep their garage doors closed and their doors locked when they are at home. They also urge women to take precautions when they are arriving home alone by making sure that no one is following them and being aware of their surroundings.