*167Dissenting Opinion by
Hoffman, J.:Appellant contends that the version of §8908 (b) of the Crimes Code1 applicable at the time of his trial unconstitutionally places the burden of proof of an essential element of the crime of theft on the criminal defendant.2
Appellant was observed on November 5, 1973, and November 8, 1973, removing typewriters and other office machines from the Pennsylvania Department of Labor and Industry Building in Harrisburg, and was charged in two separate indictments with theft of movable property.3 Following trial, appellant was convicted of both charges by a judge sitting without a jury. Post-trial motions attacking the constitutionality of §3903 (b) were filed and denied, and appellant was sentenced to a prison term of six to twenty-three months on each charge, the sentences to run concurrently.
Prior to the adoption of the new Crimes Code, all persons convicted of larceny were subject to the same penalties.4 The legislature eliminated this possibility by *168adopting §3903, which established four different grades for theft offenses.5 The version of §3903 applicable at the time appellant was tried reads in pertinent part:
“(a) Felony of the third degree. — Theft constitutes a felony of the third degree if the amount involved exceeds $2,000, or if the property stolen is a firearm, automobile, ... or other motor-propelled vehicle, or in the case of theft by receiving stolen property, if the receiver is in the business of buying or selling stolen property.
“(b) Other grades. — Theft not within subsection (a) of this section constitutes a misdemeanor of the first degree, except that if the property was not taken from the person or by threat, or in breach of a fiduciary obligation, and the actor proves by a preponderance of the evidence that:
“(1) the amount involved was $50 or more but less than $200 the offense constitutes a misdemeanor of the second degree; or
“ (2) the amount involved was less than $50 the offense constitutes a misdemeanor of the third degree. . ..” (Emphasis added).6
If the property stolen is not one of the items enumerated in §3903(a), and if the Commonwealth does not prove *169that the stolen property had a value in excess of $2,000, the defendant is guilty of a misdemeanor of the first degree, which carries a maximum penalty of five years’ imprisonment. See 18 Pa.C.S. §1104. If, however, the defendant proves that the value of the stolen property was less than $200, he can only be sentenced to a maximum of two years’ imprisonment, and if he proves that the value was less than $50, he can receive only a one-year sentence. Id. Appellant contends that §3903 (b) creates three separate crimes of theft, and that because value is an element of each crime, it is unconstitutional to place the burden of proving value on a defendant.
It is axiomatic that a criminal defendant is presumed innocent and that the Commonwealth has the burden of proving beyond a reasonable doubt “the existence of every fact necessary to constitute the crime charged.” In re Winship, 397 U.S. 358, 363 (1970), quoting Davis v. United States, 160 U.S. 469, 493 (1895). The lower court held that §3903 (b) does not shift the burden of proof of an element of the crime from the Commonwealth to the defendant: “The Commonwealth, of course, does have the burden of proving property was taken by a particular person to meet the provisions relative to ‘theft by unlawful taking’ and imposes no requirement upon a defendant to prove his innocence. The burden placed on a defendant is to show after he has been convicted that he should be punished as a perpetrator of a crime of the second or third degree rather than the first degree. This does not violate any presumption of innocence because at this stage the defendant has been found guilty. Thus the requirements of 3903 (b) which grades theft offenses are applicable merely to sentencing.” (Emphasis added). Apparently, the lower court was of the belief that §3903 created a two-step process: (1) a determination of whether the defendant is guilty of theft without regard to the value of the property stolen; and (2) a hearing to determine the degree of guilt. Such a procedure does not *170appear on the face of the statute. If the legislature intended to introduce a novel procedure for the prosecution of theft offenses, it would have done so explicitly. Thus, the lower court erroneously concluded that the defendant does not have the burden of proving value until his guilt has already been shown: under §3903 (b), if the defendant seeks to reduce his sentence by proving the value of the stolen goods, he would have to do so at trial.
Because the lower court concluded that §3903 (b) did not shift the burden of proof during a trial for theft, it did not consider the issue of whether the statute creates three separate offenses, as appellant contends. If it does, and if value is an element of each offense, §3903 (b) must be held unconstitutional because it places the burden of proving an element of the crime on the defendant.
It may be argued that the legislature established one crime of theft, a misdemeanor in the first degree. If the Commonwealth proves that the property stolen was in excess of $2,000 or that the property was a firearm or an automobile, the crime rises to a third degree felony under §3903(a). On the other hand, if the defendant proves that the value was less than $200 or less than $50, the crime is reduced to a misdemeanor of the second or third degree. Thus, the argument goes, the legislature has created one crime of theft, punishable as a misdemeanor of the first degree, and has afforded the defendant the opportunity, at trial, to prove mitigating circumstances to reduce the possible sentence. This argument, however, fails to adhere to the General Provisions of the Crimes Code announced by our legislature.
In §106 of the Code, the “Classes of offenses” are enumerated: “(a) General rule. — An offense defined by this title for which a sentence of death or of imprisonment is authorized constitutes a crime. The classes of crime are: (1) Murder of the first degree. (2) Felony of the first degree. (3) Felony of the second degree. (4) Felony of the third degree. (5) Misdemeanor of the first *171degree. (6) Misdemeanor of the second degree. (7) Misdemeanor of the third degree.” If the three grades of misdemeanors constitute separate classes of crime, it follows that conduct punishable as a misdemeanor of the second or third degree constitutes a crime separate from conduct punishable as a misdemeanor of the first degree. The language of §3903 (b) also compels this conclusion. Theft not within subsection (a) is a misdemeanor of the first degree. However, if the defendant proves that the value of the stolen property was less than $200 “the offense constitutes a misdemeanor of the second degree.” (Emphasis added). Thus, the different grades of offenses refer to actual prohibited conduct, and are not merely considerations relative to sentencing: a misdemeanor of the first degree makes criminal the theft of property having a value between $200 and $2000; a misdemeanor of the second degree involves the theft of property valued between $50 and $200; and a misdemeanor of the third degree involves property having a value of less than $50. Each grade prohibits different conduct, and, therefore, each grade constitutes a separate crime.
The determination of which offense has been committed depends upon the value of the stolen property. Value, therefore, is an element of each of the three theft crimes created by §3903 (b) ; “ ‘Element of an offense.’ Such conduct or such attendant circumstances or such a result of conduct as: (1) is included in the description of the forbidden conduct in the definition of the offense.” 18 Pa.C.S. §103. Thus the burden of proving the value of the stolen items must rest with the Commonwealth.7 *172In re Winship, supra. Consequently, that portion of the statute which requires the defendant to prove value should be declared unconstitutional. In the present case, the Commonwealth failed to sustain its burden of proof because it put forth no evidence in regard to valuation.8 Thus, appellant should only be found guilty of a misdemeanor of the third degree and should receive a maximum sentence of only one year. The sentence imposed by the court below was in excess of the statutory limit and hence was illegal.
I would vacate the judgment of sentence and remand for resentencing only.
Cercone and Spaeth, JJ., join in this dissenting opinion.
. Act of 1972, Dec. 6, P.L. 1482, No. 334, §1, eff. June 6, 1973; 18 Pa.C.S. §3903.
. Appellant’s second contention was not properly preserved for appeal. Part of the Commonwealth’s evidence against appellant consisted of office machines obtained during the search of an alderman’s office. Prior to this search, appellant had informed the police that he had sold some of the office machines to the alderman. At the alderman’s trial, the court suppressed the evidence because the search warrant was invalid. Appellant argues that the evidence is the fruit of an unlawful search and thus was improperly introduced against him. The lower court ruled that the search of the alderman’s office did not violate any of appellant’s Fourth Amendment rights. We need not pass on the propriety of that ruling because appellant failed to ñle a pre-trial motion to suppress evidence as required by Rule 323(b) of the Pennsylvania Rules of Criminal Procedure. Thus, appellant has waived any argument as to the admissibility of this evidence.
. Act of 1972, supra, n.l; 18 Pa.C.S. §3921.
. “Whoever commits larceny, is guilty of felony, and shall, *168upon conviction thereof, be sentenced to pay a fine not exceeding two thousand dollars,... or to undergo imprisonment,. .. not exceeding five (5) years, or both.” 1939, June 24, P.L. 872, §807; 18 P.S. §4807.
. Section 3903 is similar to §223.1(2) of the Model Penal Code. (Proposed Official Draft 1962).
. Section 3903 was amended, by the Act of June 17, 1974, P.L. 356, No. 118, §1, eff. imd.; 18 Pa.C.S. §3903. The amendment deleted the language italicized above, thereby relieving the defendant of the burden of proving the value of the stolen items and placing the burden on the Commonwealth. Although appellant was not sentenced until September 11, 1974, after the effective date of the amendment, his contention refers to the conduct of the trial, not the sentence imposed. The amendment also changed the method of valuation provided for in subsection (c). See n. 7, infra.
. It is true that only one indictment will be required, and that the trial court could sentence under only one oí the grades. This does not support the proposition that §3903 (b) created only one crime. The reason that only one indictment need be filed, and that only one sentence can be imposed, is that the second and third degree misdemeanors of §3903 (b) are lesser included offenses to the first degree misdemeanor. Thus, if a defendant is guilty of the theft of property worth more than $200 (but less than $2,000), he *172is obviously also guilty of the theft of property worth between $50 and $200, and the theft of property worth less than $50.
When one crime necessarily involves another, the offenses merge. Commonwealth v. Nelson, 452 Pa. 275, 305 A. 2d 369 (1973). In the present context, it is obvious that if the Commonwealth proves that the defendant .was guilty of the theft of property worth more than $200, no additional proof is needed to show that the defendant also was guilty of the theft of property worth more than $50. The lesser crimes are constituents of the more serious offense, and thus only one sentence may be imposed. Commonwealth v. Nelson, supra. See also Commonwealth v. Hill, 453 Pa. 349, 310 A. 2d 88 (1973).
. Before the June 17, 1974 amendment, §3903(c) provided:
“Valuation. — The amount involved in a theft shall be deemed to be the highest value, by any reasonable standard, of the property or services which the actor stole or attempted to steal...” Under the amended §3903 (c), value means market value, unless “such cannot be satisfactorily ascertained,” in which case value means “the cost of replacement of the property within a reasonable time after the crime.” If the value cannot be ascertained by either of these standards;» the value shall “be deemed to be an amount less than fifty dollars. . . .” Under either version, the party having the burden of proving valuation would have to produce some evidence in support of its contention. In the present case, the Commonwealth introduced no evidence at all. It is not necessary at this time to decide exactly what form and quantity of proof of value is necessary.