A woman thought to have hatched a scheme to kill her estranged husband and his pregnant girlfriend, then collect a $600,000 life insurance policy, was convicted Friday of two counts of conspiracy to commit first-degree murder, authorities said.

Sheila Aidoo, 52, reached an agreement with prosecutors that will put her in prison for no less than 10 years but no more than 20 for the January 2009 killings of Seth Aidoo, 40, her estranged husband, and Eunice Baah, 36, his pregnant girlfriend, said William Brennan, Aidoo’s defense attorney.

He said she pleaded guilty under the Alford doctrine — meaning she did not actually admit guilt but acknowledged prosecutors had enough evidence to secure a conviction.

Aidoo had not been charged with the crime itself — only conspiracy to commit it and being an accessory before and after the fact. Prosecutors have said Seth Aidoo had a $600,000 life insurance policy that listed Sheila was the beneficiary, and finances were believed to be part of the motive.

Two other men — Aidoo’s brother and boyfriend — actually made their way into Seth Aidoo’s Upper Marlboro home, then shot Baah and stabbed Seth Aidoo, authorities have said.

The boyfriend, Delford Barnes, was convicted of first-degree murder and sentenced to life in prison without parole. The brother, Samuel Culley, pleaded guilty to first-degree murder before that and was sentenced to life in prison.

Sheila Aidoo is scheduled to be sentenced in September, authorities said.

Read more: The Post’s crime coverage