November 19. On this date in 1957, the Hands of the Cause in the Holy Land released an Official Statement "That the safe and desk have been opened and searched and the non existence of a Will and Testament executed by Shoghi Effendi was definitely established." Shoghi Effendi died without having written a will as prescribed in Bahá'u'lláh's Kitáb-i-Aqdas and without having designated a successor Guardian as stipulated in `Abdu'l-Bahá's Will and Testament.

November 19. On this date in 1957, the Hands of the Cause in the Holy Land released an Official Statement "That the safe and desk have been opened and searched and the non existence of a Will and Testament executed by Shoghi Effendi was definitely established." Shoghi Effendi died without having written a will as prescribed in Bahá'u'lláh's Kitáb-i-Aqdas and without having designated a successor Guardian as stipulated in `Abdu'l-Bahá's Will and Testament.

HANDS IN THE HOLY LAND
OFFICIAL STATEMENT
Haifa, Israel
November 19, 1957
Allah-u-Abha!
This morning immediately after 9:00 a.m. we, the five Hands of the Cause assigned to service at the World Centre of the Faith, Ruhiyyih Khanum, Mason Remey, Amelia E. Collins, Ugo Giachery, and Leroy Ioas as well as Hands of the Cause Hasan Balyuzi, a member of the Afnan family, Mr. Horace Holley, representing the believers of the Western Hemisphere, Musa Banani; representing the believers of the African continent, and Dr. 'Ali-Muhammad Varqa Trustee of the beloved Guardian, representing also the Asian continent, (totaling to, 9 the number of Baha) have met, in order to open the Guardian's safe and desk [and] search for a Will and Testament if one was executed by Shoghi Effendi.
They found that the seals placed on the safe by the five Hands in the Holy Land were intact and untouched; and similarly the seals containing the keys to the safe were intact and untouched and similarly that the sealed desk was intact.
The undersigned nine Hands of the Cause, appointed by the first Guardian, Shoghi Effendi each in the presence of the others, do hereby individually and collectively certify to the following:
That the safe and desk have been opened and searched and the non existence of a Will and Testament executed by Shoghi Effendi was definitely established.
[Signed as follows]
Ruhiyyih Mason Remey Amelia E. Collins
Ugo Giachery Leroy C. Ioas Hasan M. Balyuzi Horace Holley M.B. [Musa Banani] Dr. A. Vargha

Shoghi Effendi died without having written a will as prescribed in Bahá'u'lláh's Kitáb-i-Aqdas and without having designated a successor Guardian as stipulated in 'Abdu'l-Bahá's Will and Testament.
From the Kitáb-i-Aqdas, paragraph 109...

Unto everyone hath been enjoined the writing of a will. The testator should head this document with the adornment of the Most Great Name, bear witness therein unto the oneness of God in the Dayspring of His Revelation, and make mention, as he may wish, of that which is praiseworthy, so that it may be a testimony for him in the kingdoms of Revelation and Creation and a treasure with his Lord, the Supreme Protector, the Faithful.

From The Will And Testament of ‘Abdu’l-Bahá, Part One, page 12...

O ye beloved of the Lord! It is incumbent upon the Guardian of the Cause of God to appoint in his own life-time him that shall become his successor, that differences may not arise after his passing. He that is appointed must manifest in himself detachment from all worldly things, must be the essence of purity, must show in himself the fear of God, knowledge, wisdom and learning. Thus, should the first-born of the Guardian of the Cause of God not manifest in himself the truth of the words:—“The child is the secret essence of its sire,” that is, should he not inherit of the spiritual within him (the Guardian of the Cause of God) and his glorious lineage not be matched with a goodly character, then must he, (the Guardian of the Cause of God) choose another branch to succeed him.

In 1957, the same year as Shoghi Effendi's death, When Prophecy Fails was published. In the classic work of social psychology, When Prophecy Fails, Leon Festinger, Henry Riecken, and Stanley Schachter studied a small UFO religion in Chicago called the Seekers that believed in an imminent apocalypse. They describe the coping mechanisms after the event did not occur, and their findings have been generally applicable to a wide variety of scenarios involving cognitive dissonance and true-believer syndrome.
Festinger describes the basic hypotheses of cognitive dissonance as follows (page 3):

1. The existence of dissonance [or inconsistency], being psychologically uncomfortable, will motivate the person to try to reduce the dissonance and achieve consonance [or consistency].
2. When dissonance is present, in addition to trying to reduce it, the person will actively avoid situations and information which would likely increase the dissonance.

Festinger and his co-authors conclude that the following conditions lead to increased conviction in beliefs following disconfirmation (page 4):

1. The belief must be held with deep conviction and be relevant to the believer's actions or behavior.
2. The belief must have produced actions that are difficult to undo.
3. The belief must be sufficiently specific and concerned with the real world such that it can be clearly disconfirmed.
4. The disconfirmatory evidence must be recognized by the believer.
5. The believer must have social support from other believers.

Festinger describes the increased conviction and proselytizing by cult members after disconfirmation as a specific instantiation of cognitive dissonance (i.e., increased proselyting reduced dissonance by producing the knowledge that others also accepted their beliefs) and its application to understanding complex mass phenomena. (pages 252-259)