Iran’s regime has arrested three more environmentalists on spying charges.

Continuing a crackdown on researchers and activists in which 10 people have been detained and one has died in custody, Judiciary spokesman Gholam Hossein Mohseni Ejei announced the latest detentions on Sunday.

“There is no doubt that infiltration by the United States and Israel is a serious matter,” Ejei said, without offering any further information.

The crackdown began on January 24 with Kavous Seyed-Emami, the Iranian-Canadian managing director of the Persian Wildlife Heritage Foundation and a Professor of Sociology at Tehran’s Imam Sadegh University. Authorities told Seyed-Emami’s family on February 9 that he had died in prison, claiming that he committed suicide.

The family has not accepted the explanation of the officials.

A day after the revelation of Seyed-Emami’s death, the detentions of at least seven other staff of the Persian Wildlife Heritage Foundation were confirmed.

Iranian officials have declared that the environmentalists were spying for the CIA and Israel’s Mossad, including monitoring of nuclear and missile sites, and passing sensitive “environmental data” to the Americans and Israelis. The former head of Iran’s armed forces even declared that the environmentalists could have used lizards attracting “atomic waves” to collect information on the Iranian nuclear program.

No evidence has been offered to support the claim, although State broadcaster IRIB ran a series of allegations against Seyed-Emami as questions continued over his death in Tehran’s Evin Prison.

“Given the events that have occurred, if a competent and legal agency does not intervene and doesn’t give its opinion on the dead individual or those under arrest, public opinion will not believe they are spies even if they are convicted,” said former Intelligence Minister Ali Younesi, an advisor to President Hassan Rouhani, in an interview published on Sunday.

Younesi called for the Intelligence Ministry to take over the case from the Revolutionary Guards.