Four suspects have been arrested following the deaths of 18 elephants in Kenya's Amboseli ecosystem, while authorities are searching for additional suspects, a government official said.

Rebecca Miano, Cabinet Secretary in the Ministry of Tourism and Wildlife, said in a statement issued Saturday that 15 of the elephant deaths were recorded between June 24 and July 24, with three more reported last week.

Miano said ongoing investigations had yet to establish criminal culpability. She added that the government would allow investigative and judicial processes to take their course and prosecute anyone found to have unlawfully killed, poisoned or harmed wildlife.

The Kenya Wildlife Service, working with security, investigative and scientific agencies, has intensified investigations into the cause of the deaths, Miano said. Comprehensive field investigations, laboratory analysis and environmental sampling have already been carried out.

According to Miano, preliminary laboratory results indicate the probable involvement of a toxic substance. Earlier findings suggested that cyanide poisoning may have resulted from elephants ingesting tomatoes contaminated with pesticides from farms adjacent to wildlife habitats.

However, Miano stressed that these findings remain subject to further scientific verification before the investigation can be considered complete. She said the government would strengthen monitoring of risks associated with the misuse, illegal application, trafficking or careless handling of hazardous substances that could endanger wildlife, people and ecosystems.