From objects it is possible to reconstruct elements of his career. He started as a chamberlain, then was appointed high steward, and later became treasurer.

At Dahshur, information about Siese is primarily derived from his mastaba, which was excavated by Jacques de Morgan around 1894–95 and rediscovered in 2008 by an Egyptian team. The mastaba was decorated with a palace facade and with scenes showing Siese and his family. Four panels with the image of Siese in front of an offering table were excavated by de Morgan and are now on display in the Egyptian Museum of Cairo. The burial chamber of the tomb is decorated with the Pyramid Texts. On the chamber, he is given the title "Treasurer".

Towards the end of his career he was appointed vizier.

The dating of Siese is uncertain. For a long time it has been assumed that he was in office under king Amenemhat II, as his mastaba is close to that of this king. However, in his mastaba appear scenes showing single family members sitting on the ground with a small pile of offerings in front of them. This type of scene is only attested from the reign of king Senusret III onwards. Furthermore, the realistic depiction of Siese's face had parallels in on reliefs in the mastaba of Sobekemhat, who dates under Senusret III. These observations indicate that Siese dates under this king. ^[1]

• Wolfram Grajetzki: Court Officials of the Egyptian Middle Kingdom, London 2009 p. 56-57, pl. 2 ISBN 978-0-7156-3745-6
• Samy el-Husseiny, Adel Okasha Khafagy: The Dahshur tomb of Vizier Siese rediscovered, In: Egyptian Archaeology 36 (2010), p. 21-24
• William Kelly Simpson: Lepsius Pyramid LV at Dahschur: the Mastaba of Si-Ese, Vizier of Amenemhet II, In: Pyramid studies and other essays presented to I. E. S. Edwards, John Baines [Hrsg.], London 1988, p. 57–60, ISBN 0-85698-106-0
• William Kelly Simpson: Rulers and Administrators - Dynasty 12, The Rule of the House of Itj-towy with Some Personal Reminiscenes, In: D. P. Silverman, W. K. Simpson, J. Wegner (Hrsg.): Archaism and Innovation: Studies in the Culture of Middle Kingdom Egypt, New Haven, Philadelphia 2009 p. 302 ISBN 978-0-9802065-1-7

• The Tomb of Sa-Iset at Dashur