SAN DIEGO -- Two people accused in a home-invasion robbery in which a woman was raped, and she and four others were tied up and doused with lighter fluid, pleaded not guilty Tuesday to four added sexual assault charges.

Kevin Keith Sellers and Vanna Chheun, both 30, each faces up to 150 years to life in prison if convicted of a total of 30 charges, said Deputy District Attorney Rachel Cano.

The defendants were charged last October with five counts each of kidnapping for robbery, robbery, assault with caustic chemicals and making a criminal threat. In addition, Sellers and Chheun were charged with two counts of rape and one count each of rape in concert, oral copulation, oral copulation in concert and residential burglary.

Today, Cano added one count each of forcible rape, oral copulation, digital penetration and attempted sodomy.

A third man, Tommy Nguyen, remains at large but is also charged in the case, the prosecutor said.

A preliminary hearing is scheduled for April 7.

Cano alleges that Sellers and another male -- later identified as Nguyen -- entered the home in the 5900 block of Hughes Street before midnight on Oct. 17 and tied up three men at gunpoint.

The intruders bound both the hands and feet of the victims and covered their heads with sheets, Cano said. At some point, Chheun came in the house and stood guard over the victims, sipping on wine coolers, the prosecutor alleged.

Sellers and Nguyen -- also known as Trieu Nguyen -- then ransacked the house, taking jewelry, cell phones, cash and laptop computers, and even the eyeglasses one of the victims was wearing, the prosecutor alleged.

The victims were doused with lighter fluid and repeatedly told they would be killed unless they came up with $20,000, according to Cano.

During the robbery, a husband and wife arrived at the home and both were tied up, the prosecutor said.

The female victim -- with her hands tied behind her back -- was dragged into a bedroom and allegedly raped by Sellers and Nguyen.

The woman's husband and the three original victims were then dragged into the bedroom, where all five victims were doused with lighter fluid, Cano said.

Though her hands were bound, the female victim was able to dial 911, the prosecutor said.

Chheun was arrested as she left the residence, and Sellers was caught as he tried to jump over a back fence, according to the prosecutor.