Following ‘Abdu’l‑Bahá’s instructions the remains were finally laid to rest in the Holy Land

…from whence [Imám-Zádih-Hasan in Tihrán] they were removed to different places, until the time when, in pursuance of ‘Abdu’l‑Bahá’s instructions, they were transferred to the Holy Land, and were permanently and ceremoniously laid to rest by Him in a specially erected mausoleum on the slopes of Mt. Carmel. 

- Shoghi Effendi  (Chapter 4, God Passes By)

In accordance with Bahá’u’lláh’s instruction the remains were transferred to Tihrán

No sooner had the news of the transfer of the remains of the Báb and of His fellow-sufferer been communicated to Bahá’u’lláh than He ordered that same Sulaymán Khán to bring them to Tihrán, where they were taken to the Imám-Zádih-Hasan,… 

- Shoghi Effendi  (Chapter 4, God Passes By)

The claims of the clergy concerning the disappearance of the body of the Báb

Meanwhile the mullás were boastfully proclaiming from the pulpits that, whereas the holy body of the Immaculate Imám would be preserved from beasts of prey and from all creeping things, this man’s body had been devoured by wild animals. 

- Shoghi Effendi  (Chapter 4, God Passes By)