For 40 years, Janine Phillips Africa had a technique for coping with being cooped up in a prison cell for a crime she says she did not commit. She would avoid birthdays, Christmas, New Year and any other events that emphasized time passing while she was not free.

“The years are not my focus,” she wrote in a letter to the Guardian. “I keep my mind on my health and the things I need to do day by day.”

On Saturday she could finally begin accepting the passage of time. She and her cellmate and sister in the black liberation struggle, Janet Holloway Africa, were released from SCI Cambridge Springs in Pennsylvania, after a long struggle for parole.

The release of Janine, 63, and Janet, 68, marks a key moment in the history of the Move 9, the group of African American black power and environmental campaigners who were imprisoned after a police siege of their home in August 1978. The pair were the last of four women in the group either to be paroled or to die behind bars.

The saga of Move was one of the most dramatic and surreal of the 1970s black liberation struggle. Along with their peers, the women lived in a communal house in Philadelphia under group founder John Africa, AKA Vincent Leaphart. All members took the last name Africa to show they considered themselves a family.

A cross between the Black Panthers and west coast hippies, Move campaigned not only for equal treatment for African Americans but also for respect for animals and nature, caring for 48 stray dogs in the house.

Such unconventional attitudes brought them into conflict with neighbours and the Philadelphia police, a notoriously brutal force even by American standards. After a siege lasting several months, on 8 August 1978 officers went in to clear the group from the property. In the melee, officer James Ramp was shot and killed with a single bullet.

Despite the single shooter, and despite the fact that the group always protested that they were unarmed and that Ramp was killed by fire from fellow officers, the five men and four women were each sentenced to 30 years to life.

Janine and Janet Africa upon their release. Photograph: Handout

Janine Africa’s release was bittersweet. While she was in prison, she corresponded over two years with the Guardian. In her letters she talked about the double tragedy of her life.

Two years before the 1978 siege, police turned up at the Move house in Powelton Village and began harassing the group. A scuffle ensued and Janine was knocked over as she held her three-week-old baby, Life, in her arms.

The baby appeared to have been trampled, his skull shattered. He died later that day.

Then on 13 May 1985, by which time Janine Africa had been in prison for seven years, she was told the terrible news that the remaining members of the Move “family” had been assaulted a second time. On this occasion police didn’t just go in guns blazing – they dropped an incendiary bomb from a helicopter.

It caused a fire that destroyed the Move house and 60 other homes in a largely African American neighborhood. Eleven Move members burned to death. They included founder John Africa and five children, one of whom was Janine’s other son, Little Phil, aged 12.

The Guardian asked Janine how she came to terms with having seen two children killed by police brutality.

Janine Phillips Africa, whom the Guardian corresponded with from her prison cell. Photograph: Leif Skoogfors/Corbis via Getty Images

“There are times when I think about Life and my son Phil,” she wrote, “but I don’t keep those thoughts in my mind long because they hurt. The murder of my children, my family, will always affect me, but not in a bad way. When I think about what this system has done to me and my family, it makes me even more committed to my belief.”

The parole of the two women follows the release last June of Debbie Sims Africa, who was arrested in the 1978 siege when she was eight months pregnant and who went on to give birth to her son, Michael Davis Jr, in a prison cell. A fourth woman, Merle Austin Africa, died in prison in March 1998.

Of the men, three remain in prison: Eddie Goodman Africa, who has recently gone before a parole panel, and Chuck Sims Africa and Delbert Orr Africa. Michael Davis Africa Sr, the father of the boy born in a cell and husband of Debbie, was released in October. Phil Africa died in prison in January 2015.

The attorney for the two released women, Brad Thomson of People’s Law Office, said their parole was a victory not only for them and their loved ones but also for the Move organization and the “movement to free all political prisoners”. He pointed out that prison staff had described them as model prisoners and that neither has had a single disciplinary incident in more than 20 years.

“While in prison, they have participated in community fundraisers and social programs including training service dogs,” Thomson said. “They are remarkable women to deserve to be free.”

The Guardian corresponded with Janine Africa as part of a journalistic project to chronicle the lives of 19 black radicals who then remained behind bars. She described how having been arrested at 22 she went on to share a cell with Janet and Debbie Africa.

Over 40 years they kept their spirits up by caring for a dog kennelled in their cell which they trained to work with vulnerable individuals. They also helped younger female prisoners and grew vegetables in the prison grounds.

Janine and Janet Africa are likely to return to live in Philadelphia. The Move organization still exists in the city, where it continues to campaign on issues of racial justice and environmental protection.

Neither Debbie nor her husband Michael Sr have had any infractions or violations under their parole terms since they were released. Once joined by their colleagues, they will press for the release of the three remaining members of the Move 9.