Carl Youngblood, an African-American, instituted a civil rights action against Hy-Vee Food Stores, Inc. (Hy-Vee), asserting that Hy-Vee violated his rights under 42 U.S.C. §§ 1981 and 1983 and also subjected him to malicious prosecution and false imprisonment when they detained him on suspicion of shoplifting and had him arrested and pressed charges against him. The district court2 granted Hy-Vee summary judgment, concluding that Hy-Vee’s actions did not deprive Youngblood of his right to contract under Section 1981, as Youngblood had completed his purchase; that Hy-Vee did not violate the full-and-equal-benefits clause of Section 1981, as its actions constituted private and not state action; that because Hy-Vee’s actions did not constitute state action, Youngblood’s Section 1983 claim likewise failed; and that Youngblood could not establish malicious prosecution or false imprisonment, as there was probable cause for his arrest and his detention was reasonable.
On appeal, Youngblood argues that the contract rights protected by Section 1981 include the right to the enjoyment of all benefits, privileges, terms, and conditions of the contractual relationship, and that the district court therefore erred in concluding that Section 1981 provided Young-blood no protection once he completed the contract by making his purchase. Young-blood further argues that the full-and-equal-benefits clause of Section 1981 applies to private actors, and that, in any event, Hy-Vee acted under color of state law so as to implicate Youngblood’s rights under both Sections 1981 and 1983. Finally, Youngblood argues that probable cause did not exist to arrest him and thus, summary judgment was inappropriate on his malicious-prosecution and false-imprisonment claims.
For reasons stated herein, we AFFIRM the decision of the district court.
1. Background.
On or about April 13, 1998, Youngblood entered Hy-Vee and proceeded to the section of the store that contained canisters of beef jerky. Youngblood spent some time in this area before selecting a canister and walking up the aisle towards the check-out area. A store employee observed Young-blood and thought his behavior unusual for it appeared to the employee that Young-blood had his hands underneath his shirt. After taking a few steps up the aisle, Youngblood turned and returned to the beef-jerky section, placed the original canister back on the shelf and picked up another canister. It appeared to the store employee that Youngblood placed the second canister underneath his shirt. Young-blood then proceeded to the cash register and purchased a single canister of beef jerky. The store employee checked the canister Youngblood placed back on the shelf and discovered that most of the beef jerky inside was missing. As Youngblood headed toward the exit, the employee stopped Youngblood and asked for his receipt. Youngblood gave him the receipt and his bag. The store employee opened the canister Youngblood had purchased and observed that it was “crammed full” of beef jerky. The stop of Youngblood in the front of the store lasted two to five minutes and Youngblood then waited in an upstairs office for approximately twenty *854minutes until the police arrived. The door to the office remained open during this time and Youngblood was not physically restrained in any manner. When the police officer arrived, he asked what Young-blood had done and the store employee told the officer that Youngblood had taken most of the contents of one beef-jerky canister and placed it into another. After examining the contents of the canister, the officer arrested Youngblood. The criminal charges against Youngblood were ultimately dismissed.
II. Discussion.
We review the district court’s grant of summary judgment de novo. See Beck v. Skon, 253 F.3d 330, 333 (8th Cir.2001). We reverse an award of summary judgment only if we find that a material issue of fact exists or that the district court made an incorrect conclusion of law. See Fed.R.Civ.P. 56(c). In deciding whether Hy-Vee is entitled to summary judgment, we view the summary judgment record in a light most favorable to Youngblood, affording him the benefit of all reasonable inferences. See Tlamka v. Serrell, 244 F.3d 628, 632 (8th Cir.2001).
A. Section 1981’s Right-to-Contract Clause
Section 1981 provides that all persons shall have the same right to “make and enforce contracts.” See 42 U.S.C. § 1981(a). In 1991, Congress expanded the scope of Section 1981 to include the right to “the enjoyment of all benefits, privileges, terms, and conditions of the contractual relationship.” See 42 U.S.C. § 1981(b). Hy-Vee removed the beef jerky from Youngblood after the point of purchase and Hy-Vee did not refund Youngblood’s money even after the charges against him were dismissed. Hy-Vee further did not return the beef jerky to Youngblood as Hy-Vee discards all damaged items associated with a suspected shoplifting. The question we must determine is whether any contractual relationship remained once Youngblood completed his purchase and if the taking of the beef jerky denied Youngblood a benefit of the contractual relationship.
While there is scant precedent, courts that have addressed the issue have concluded that once the purchase is completed, no contractual relationship remains. See e.g., Lewis v. J.C. Penney Co. Inc., 948 F.Supp. 367, 372 (D.Del.1996); see also Rogers v. Elliott, 135 F.Supp.2d 1312, 1315 (N.D.Ga.2001). Youngblood correctly points out that in these cases the customers did not have the merchandise they purchased taken away. This distinction is of little significance, however, as the key is whether any contractual duty remained after Youngblood made his purchase. Once Youngblood paid the cashier and received the beef jerky from the cashier, neither party owed the other any duty under the retail-sale contract. This case is distinguishable from Hampton v. Dillard Dept. Stores, Inc., 247 F.3d 1091 (10th Cir.2001), where the Tenth Circuit found a contractual relationship existed after the purchase. In Hampton, the customer received a coupon for a fragrance sample as a benefit of her purchase and the Tenth Circuit concluded that the store had a contractual duty to allow the customer to redeem the coupon. See id. at 1103-05. In this case, nothing that happened after the sale created any further contractual duty on Hy-Vee’s part. Accordingly, Hy-Vee cannot be said to have deprived Youngblood of the benefit of any contractual relationship, as no such relationship existed when it took the beef jerky away from Youngblood.
The dissent suggests that Young-blood was blatantly discriminated against *855in this case. While we disagree, Section 1981 does not provide a general cause of action for race discrimination if in fact it occurred. The requirement' remains that a plaintiff must point to some contractual relationship in order to bring a claim under Section 1981. This conclusion does not mean that there is no remedy in cases where a store wrongfully confiscates items purchased by a customer. The nature of the action, however, is not in contract, but in tort. Specifically, under Missouri law, a cause of action for conversion lies for the tortious taking of a chattel. See Koger v. Hartford Life Ins. Co., 28 S.W.3d 405, 415 (Mo.Ct.App.2000).
B. Section 1981’s Full-and-Equal-Benefit Clause
Section 1981 provides that all persons shall have the right to “the full and equal benefit of all laws and proceedings for the security of persons and property.” 42 U.S.C. §■ 1981(a). “Because the state is the sole source of the law, it is only the state that can deny the full and equal benefit of the law.” Chapman v. Higbee Co., 256 F.3d 416, 2001 WL 753504, *3 (6th Cir. July 5, 2001); see also Mahone v. Waddle, 564 F.2d 1018, 1029 (3d Cir.1977) (concept of state action is implicit in full- and-equal-benefit clause), cert. denied, 438 U.S. 904, 98 S.Ct. 3122, 57 L.Ed.2d 1147 (1978). As discussed below, Hy-Vee’s actions did not constitute state action and Hy-Vee was therefore entitled to summary judgment on Youngblood’s claim under the full-and-equal-benefit clause.
C. Section 1983
Only state actors can be held liable under Section 1983. See Adickes v. S.H. Kress & Co., 398 U.S. 144, 150, 90 S.Ct. 1598, 26 L.Ed.2d 142 (1970). A private party who willfully participates in joint activity with the State or its agents is considered a state actor. See id. at 152, 90 S.Ct. 1598. A store may be considered to be acting jointly with police when the police detain accused shoplifters without making an independent investigation or pursuant to a customary plan between the store and the police department. See Murray v. Wal-Mart, Inc., 874 F.2d 555, 558-59 (8th Cir.1989). In Murray, the court found that Wal-Mart acted in concert with the police because Wal-Mart had a practice of working with the police department in prosecuting shoplifters; the store security guard was an employee of the police department; and the police relied on the guard’s incomplete version of the facts without any independent investigation. See id. at 559.
The present case is distinguishable from Murray, as the store employee who witnessed the incident was not employed by the police department and the police officer summoned to the scene investigated the incident by speaking with the store employee and examining the contents of the beef jerky canister. Young-blood relies on a state statute which authorizes merchants to detain suspected shoplifters in a reasonable manner and for a reasonable length of time to investigate whether there has been a shoplifting, see Mo.Rev.Stat. § 537.125 (2000), and argues that as Hy-Vee acted under this statute, its conduct constituted state action. The Supreme Court has held that a private party’s mere invocation of state legal procedures does not constitute state action. See Lugar v. Edmondson Oil Co., 457 U.S. 922, 939 n. 21, 102 S.Ct. 2744, 73 L.Ed.2d 482 (1982); cited in Miller v. Compton, 122 F.3d 1094, 1098 (8th Cir.1997).
D.State-Law Claims of Malicious Prosecution and False Imprisonment
The district court properly granted Hy-Vee summary judgment on these *856claims, as probable cause existed to suspect Youngblood of shoplifting. See Jacobs v. Bonser, 46 S.W.3d 41, 49 (Mo.Ct.App.2001) (to make submissible case of malicious prosecution, plaintiff must show lack of probable cause for prosecution); Edwards v. McNeill, 894 S.W.2d 678, 683 (Mo.Ct.App.1995) (probable cause is complete defense to cause of action for false arrest). A store employee thought he observed Youngblood put a canister of beef jerky under his shirt, then return that canister to the shelf and place another one under his shirt. The employee examined the can placed back on the shelf and only a couple of pieces remained in it. When the employee examined the canister Young-blood had purchased, it appeared to be “crammed full.” These facts provided “reasonable grounds for suspicion, supported by circumstances ... sufficiently strong to warrant a cautious man in his belief’ that Youngblood had committed the offense of shoplifting. See Thompson v. Wal-Mart Stores Inc., 890 S.W.2d 780, 782 (Mo.Ct.App.1995).
III. Conclusion.
Based on the foregoing, we hereby affirm the district court’s rulings in their entirety.
. The Honorable Fernando J. Gaitan, Jr., United States District Judge for the Western district of Missouri.