Yishai Schlissel, who is serving a life sentence for his deadly stabbing spree at last year’s Jerusalem pride parade, was arrested in prison for planning a violent plot on this year’s march.

Hours before the start of Thursday’s parade, Israel Police cleared for release the arrest of Schlissel in prison Wednesday on charges of conspiracy to commit a crime and for planning an attack on the parade.

Schlissel reportedly hatched the plot with his brother, Michael, to attack march participants and not to allow the march to go off peacefully.

Michael Schlissel also was arrested Wednesday on suspicion of planning an attack on this year’s event and will be kept in prison until after the march, according to reports.

Their mother and four other siblings were ordered out of Jerusalem until after the march as well, though their home is in the city. They were all questioned by police on Wednesday, according to reports.

Police have said the march will take place as planned. Heightened security plans for the march were unveiled earlier this week.

Yishai Schlissel stabbed six marchers at the 2015 parade, killing one — Shira Banki, 16.

He had been released from prison several weeks before the parade after serving 10 years for a similar attack at the Jerusalem gay pride parade in 2005. In the days leading up to last year’s parade, the haredi Orthodox Schlissel expressed his opposition to the march in interviews and in ads in haredi synagogues in Jerusalem and Kiryat Sefer.

Police initially turned away Schlissel at an entrance point to the parade, but he found a way in later in the route.

The parade is to be held under tight security and is dedicated in memory of Banki.