It seems to be that this claim originated from Criminal Justice International Associates (CJIA). They seem to have one person affiliated with their organization, the same person cited in the source, "Jerry Brewer". In the comments to the question, someone found their website. On it was a phone number which helped me find this site which they had made with Google. CJIA refers to itself as a A Global Threat Mitigation Firm, which seems vague and Stratfor-ish.

Linked on CJIA's Google Site, I was able to find Brewer's bio. Jerry Brewer however does claim a lot of experience,

Mr. Brewer is a U.S. Government-trained counterterrorism specialist and senior trainer, with extensive operational activity in Latin America and the Middle East as an intelligence community operative. Fluency in Spanish (Castilian). He has over thirty years of professional managerial and leadership experience in the field of Criminal Justice; fifteen (15) years as Chief of Police (3 states)- U.S. Congressional and State Senate and House, honors for: “…bravery and salient actions; quick and unflinching response, and exemplary citizenship he has manifested in going above and beyond the call of duty to assure the safety of others.”

He works as an expert witness on "complex law enforcement operational issues including death/homicide," needless to say at this point it seemed like making a claim about the wealth of the president of a foreign nation is out of his paygrade.

Also on his Google Site was a link to his WordPress blog. On that blog, you can find Brewer's paper authored in November 27, 2011 about Chávez entitled "Hugo Chavez's Abuse of Power and Corruption". Writing about the 2012 Venezuela elections, he said,

A freedom loving Venezuelan populace is determined to take back their country in the 2012 elections and restore a “true democracy.”

Clearly, that's untrue. In the 2012 Venezuela elections, Chávez won with an 11% margin. That's an electoral landslide. Aside from being disconnected from facts, Brewer's bias is abundantly apparent in the document,

As a devout worshipper and follower of his hero and mentor Fidel Castro, he took up the banner of Cuba's failed revolution of atrocities, human rights abuses, and Cuba‟s shameful misery; and essentially claimed the dubious honor of leading the blind- through corruptive influences, hidden motives and opportunities, and much impunity of action.

Alas though the 2011 PDF isn't the only one authored by CJIA on Venezeula, Brewer published the four page "The Death of Hugo Chavez Surrounded in Veil of Concealment" on March 6, 2013. In it, the only mention of any estate of Chávez is assumed from this,

Little was done to curb Venezuela’s safety from homicides and related violent crime that are setting world records. Gifts and significant discounts of oil to Cuba and others, severely crippled the Venezuelan economy with essentially no paper or record of this massively squandered Venezuelan oil revenue. He consistently refused to explain how such an oil-rich country had fallen financially and failed the people. The squandering and unaccountability of Venezuela's vast oil revenues remains a mystery to the Venezuelan populace.

There is no further mention in even this most recent document of Chávez's wealth. It is worth explicitly mentioning that it's pretty naive and shortsighted to say that an oil subsidy to Cuba resulted in a severe crippling of the Venezuela's economy.

Brewer seems to be eccentric character that doesn't like citing his facts. It seems consistent with his character and anti-Chávez positions to make such a statement, and also consistent not to cite that statement. I wouldn't put any weight in Brewer's authority and the statement is otherwise unsubstantiated.

If you'd like to read some other not-so-interesting articles written by Brewer you can check out Brewer's Scribd page.