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Washington, D.C. 20549

(Name of Issuer)

Ordinary Shares

(Title of Class of Securities)

767271109

(CUSIP Number)

December 31, 2008

(Date of Event Which Requires Filing of this Statement)

 

 

CUSIP No.		767271109

CUSIP No.		767271109

¹    ING Life Insurance and Annuity Company is a wholly owned indirect subsidiary of ING Groep N.V.

CUSIP No.		767271109

Item 1(a). Name of Issuer:

Rio Vista Energy Partners L.P.

Item 1(b). Address of Issuer’s Principal Executive Offices:

1313 E. Alton Gloor Blvd.
Suite J
Brownsville, Texas 78526

Item 2(a). Name of Person Filing:

ING Groep N.V.
ING Life Insurance and Annuity Company

Item 2(b). Address of Principal Business Office or, if None, Residence:

ING Groep N.V.
Amstelveenseweg 500
1081 KL Amsterdam
P.O. Box 810
1000 AV Amsterdam
The Netherlands

ING Life Insurance and Annuity Company
One Orange Way
Windsor, Connecticut 06095-4774

Item 2(c). Citizenship:

See item 4 on Page 2
See item 4 on Page 3

Item 2(d). Title of Class of Securities:

Common Units

Item 2(e). CUSIP Number:

767271109

Item 3.		If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a: (Not Applicable)

		(a)		o		Broker or dealer registered under Section 15 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”);
		(b)		o		Bank as defined in Section 3(a)(6) of the Exchange Act;
		(c)		o		Insurance company as defined in Section 3(a)(19) of the Exchange Act;

CUSIP No.		767271109

		(d)		o		Investment company registered under Section 8 of the Investment Company Act of 1940, as amended (the “Investment Company Act”);
		(e)		o		Investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E) under the Exchange Act;
		(f)		o		Employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F) under the Exchange Act;
		(g)		o		Parent holding company or control person in accordance with Rule 13d-1(b)(ii)(G) under the Exchange Act;
		(h)		o		Savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;
		(i)		o		Church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act;
		(j)		o		Group in accordance with Rule 13d-1(b)(1)(ii)(J) under the Exchange Act.

Item 4. Ownership. ²

(a)

Amount beneficially owned:

See item 9 on Page 2

See item 9 on Page 3

(b)

Percent of class:

See item 11 on Page 2

See item 11 on Page 3

²   Ownership is calculated on the basis of the currently exercisable portion of a warrant issued by the Issuer to TCW Energy Funds X Holdings, L.P. (“Holdings”). ING Life Insurance and Annuity Company (“ILIAC”) holds a 6.81556% equity interest in Holdings.

TCW Asset Management Company (“TAMCO”) serves as discretionary investment manager to ILIAC with regard to its investment in Holdings pursuant to an Amended and Restated Investment Management and Custody Agreement dated as of December 3, 2004 among ILIAC, TAMCO and Trust Company of the West. If the warrant were exercised, ILIAC and TAMCO would have shared power to vote (or direct the vote) and dispose of (or direct the disposition of) common units of Rio Vista.

The warrant provides that Holdings may, until a demand loan (“Demand Loan”) advanced by an affiliate of Holdings is repaid in full, purchase common units in the Issuer in an amount determined by dividing the outstanding principal amount then owed on the Demand Loan by an exercise price equal to the lower of (A) $13.33 per common unit, and (B) 90% multiplied by the average of the closing prices for a common unit for the 20 trading days immediately preceding the date of Holdings’ election to exercise. In addition, as of November 19, 2008, Holdings has the right to convert debt owed by the Issuer under a senior credit facility (“Credit Facility”), net of the Demand Loan, but including accrued interest and expenses on the remaining principal amount, into additional common units of the Issuer at a price equal to 90% of the 20-day average trading price of such units preceding the election to convert. As of November 30, 2008, Holdings had the right to convert $2.25 million under the terms of the Demand Loan and $23.26 million under the terms of the Credit Facility. Holdings did not elect to convert any portion of either the Demand Loan or the Credit Facility at that time. Assuming that Holdings had made an election to convert all of the outstanding amounts under the Credit Facility and the Demand Note, as of December 31, 2008, Holdings would have been entitled to receive 33,502,660 common units, equaling 92.38% of the total, as calculated in accordance with the rules under Section 13(d). Assuming that Holdings had made an election to convert all of the outstanding amounts under the Credit Facility and the Demand Note as of December 31, 2008, ILIAC’s indirect interest in the warrant would have entitled it to receive an indirect interest in 2,283,394 common units, equaling 6.30% of the total, as calculated in accordance with the rules under Section 13(d).

CUSIP No.		767271109

(c)

Number of shares as to which such person has:

	(i)		Sole power to vote or to direct the vote:
			See item 5 on Page 2
			See item 5 on Page 3
	(ii)		Shared power to vote or to direct the vote:
			See item 6 on Page 2
			See item 6 on Page 3
	(iii)		Sole power to dispose or to direct the disposition of:
			See item 7 on Page 2
			See item 7 on Page 3
	(iv)		Shared power to dispose or to direct the disposition of:
			See item 8 on Page 2
			See item 8 on Page 3

Item 5. Ownership of Five Percent or Less of a Class.

Not Applicable
o

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Not Applicable

Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8. Identification and Classification of Members of the Group.

Not Applicable

Item 9. Notice of Dissolution of Group.

Not Applicable

Item 10. Certification.

By signing below we certify that, to the best of our knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No.		767271109

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

CUSIP No.		767271109

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

CUSIP No.		767271109

Exhibit A to Schedule 13G

Joint Filing Agreement
Pursuant to Rule 13d-1(k)

The undersigned persons (the “Reporting Persons”) hereby agree that a joint statement on this Schedule 13G, and any amendments thereto, be filed on their behalf by ING Groep N.V.

Each of the Reporting Persons is responsible for the completeness and accuracy of the information concerning each of them contained therein, but none of the Reporting Persons is responsible for the completeness or accuracy of the information concerning any other Reporting Person.