A gratuitous promise, even if based on something being morally right, does not create a contract unless the beneficiary promises something else in return. Generally, such one way promises are not enforceable, although there are exceptions that are best discussed in person with an attorney.
As for the break-in, you can certainly file a police report and begin the investigation, but only a person appointed as executor or administrator of the estate can truly "press charges," take recovery of the property, or sue him over the thefts. If the brother is named as executor in the will, you should hire an attorney to assist in ensuring that the court does not permit him to serve.
Attorney Rosenberg is admitted to practice in Connecticut and Massachusetts, and currently practices in South-Central Connecticut with an emphasis on estate planning, elder law, probate, and tax matters. He may be contacted confidentially by email at Scott@ScottRosenbergLaw.com or by phone at (203) 871-3830. All correspondence through this website appears publicly, is not confidential, and does not create an attorney-client relationship between you and Atty. Rosenberg. Discretion should always be employed when posting personal information online. ~~~~~~~~~~~~~ All online content provided by Atty. Rosenberg on this and other websites is provided for general informational purposes only, and does not constitute legal advice. All content is general in nature. Attorneys are unable to ask the questions necessary to fully understand the legal issues faced by any particular poster. Postings and responses to questions only provide general insights on the topic discussed. They are not tailored to any readerâ€™s specific situation, will not be accurate in all states, and are never updated or maintained to reflect changes in the law. No person should take action based on the information provided by anyone on Avvo.com or any other law-themed website without first consulting a local attorney with significant experience in your area of concern. Persuant to Circular 230, no online content may be used by any person to avoid taxes or penalties under the Internal Revenue Code.