Responsa על גיטין 103:5

Q. An insane person fell heir to an estate. In his locality, however, no Jewish court exists to declare him insane and thus to permit the appointment of a trustee to manage the estate for his benefit. May a court declare him insane upon the testimony of two witnesses who have observed him in his locality?
A. If the testimony of two witnesses is sufficient to deprive a person of his life, it should be sufficient to declare him insane and incapable of managing his affairs. The trustee thus appointed would have complete charge of his affairs, and, if need be, would be permitted even to provide him with a wife.
This Responsum is addressed to: "My teacher and relative Rabbi Yakar haLevi".
SOURCES: Cr. 160.

Q. How are we to invest money belonging to orphans; are we permitted to lend such money on interest?
A. The Talmud provides that such money be invested with a rich and trustworthy person, one who obeys the laws of the Torah and is careful not to bring upon himself a ban of the Rabbis. It should be invested on condition that the orphans share in the profits but not in the losses (B. M. 70 a). To invest such money in mortgages on houses, fields, or vineyards, is preferable, since money may be lost but land lasts forever. The written contract attesting the transaction, should be deposited with a trustworthy person or with the trustee of the orphans. But, we are not permitted to lend such money on a definite rate of interest.
SOURCES: L. 235.