SEATTLE — An Oregon woman has been sentenced to life in prison for throwing her autistic 6-year-old son over 100 feet to his death from a bridge in the coastal town of Newport in 2014, prosecutors said on Tuesday.

Jillian McCabe, 36, pleaded guilty in Lincoln County Circuit Court on Monday to murdering her son London, District Attorney Michelle Branam said in a statement.

McCabe “was very calculated” in planning the homicide weeks in advance, Branam said, leaving behind a trail online and in phone records that showed she had researched legal defenses based upon findings of insanity and also appeared to fake mental illness and manipulate doctors.

“Based on the searches on her phone, you could surmise Jillian planned to murder London by throwing him off the bridge and to get committed to the State hospital,” Branam said.

She added that, at one point, McCabe searched online: “Can you die falling 133 ft in water?”

Authorities say McCabe called police on Nov. 3, 2014, to report that she had thrown her son from the Yaquina Bay Bridge in Newport, a town of some 10,000 about 115 miles southwest of Portland.

Branam said an autopsy found the fall did not kill London. He suffered broken bones after the impact and ultimately drowned.

The U.S. Coast Guard sent two boats and a helicopter to help search for London before his body was spotted in the water near the Embarcadero Resort, about a mile from the bridge, by a diner about four hours after she reported the incident, police said.

A website previously set up by McCabe to seek financial aid, helpmatt.org, described her family as facing financial challenges after a brain injury landed her husband, Matt, in hospital for four months last year and left him unemployed upon his release.

“With London’s autism, the financial and emotional load of Matt not being there for month after month is more than most of us can understand,” she wrote on the website.

McCabe’s admission of guilt followed a plea deal under which prosecutors agreed to drop additional charges of aggravated murder and manslaughter, the Oregonian newspaper reported.

McCabe, who received a life sentence in prison, can seek parole after serving 25 years, Branam’s office said.

She was previously scheduled to face trial in August.

An attorney for McCabe could not immediately be reached.