Just 10 days before jury selection starts in her trial, Amy Senser was charged with a third felony criminal vehicular-homicide offense alleging she was talking on a cellphone when she struck and killed a man on an interstate highway exit ramp.

The amended charge, filed in Hennepin County District Court Thursday, states that Senser was operating her vehicle in a "grossly negligent manner," causing Anousone Phanthavong's death. According to the charge, cellphone records show that Senser was on her phone at the time of the crash. It also said that a crash reconstruction expert has opined that "there is no reason the Mercedes could not have been going 50-55 miles per hour at this point on the exit ramp," which was in a construction zone.

Senser, 45, is already facing two felony charges for leaving the scene of an accident and failing to alert law enforcement about it as quickly as possible.

Eric Nelson, Senser's attorney, said Friday that he wouldn't comment on the new charge or its timing until a pretrial court hearing Monday. He didn't know if the new charge would delay the start of the trial on April 23. The new charge doesn't require Senser to turn herself in, he said.

The new criminal vehicular-homicide charge isn't considered more serious than the two others she is already facing, said Nelson. There are at least a half-dozen "subdivisions" that can constitute criminal vehicular homicide, such as drunken driving, gross negligence or being under the influence of drugs, he said.

Senser has pleaded not guilty to the charges she struck Phanthavong, 38, at the Riverside Avenue exit ramp as he was filling his car with gas, then fled the scene. Nelson contends Senser didn't realize she struck Phanthavong when she became lost en route to picking up her daughter from a concert at the Xcel Energy Center that night.

The next day, Nelson directed investigators to the damaged Mercedes sport-utility vehicle parked in the garage of the Sensers' Edina home. Ten days later, Amy Senser acknowledged that she was the driver.

A wrongful death suit has also been filed against Senser and her husband, former Minnesota Vikings star Joe Senser.

Earlier this week, Nelson filed a motion asking a Hennepin County judge to prohibit prosecutors from asking witnesses about Senser's drinking habits during her trial. In the motion, he requested an order from the judge stopping Assistant Hennepin County Attorney Deborah Russell from implying that Senser's long-standing refusal to discuss the incident with police points toward her guilt.

In September, Nelson told the Star Tribune that Senser will base her defense on a recent Minnesota Supreme Court reversal of a man's conviction in a similar case where the state failed to prove that he knew he struck and killed a man changing a tire when he left the scene. The Supreme Court's 2010 decision in the case of Mohammed Al-Naseer effectively means that prosecutors must now prove criminal intent by drivers who leave the scene of accidents, said Nelson.

David Chanen • 612-673-4465