If you live in Texas and a relative in Nigeria has passed away, you may be entitled to a share of their estate or need to administer it. To act from abroad, you will usually have to send Nigeria a document it recognizes as authentic, such as a power of attorney appointing a representative, or a US death certificate. Because Nigeria is not part of the Hague Apostille Convention, a Texas document needs a full chain of authentication before it will carry legal weight there.