The town of Ware (Ware), as assignee of Randall Witkos, brought an action to require the town of Hardwick (Hardwick) to pay to Ware statutory “injured on duty” benefits under G. L. c. 32, § 85H, allegedly due to Witkos on account of an aneurysm that disabled him while he was performing his *326duties as a part-time police officer for Hardwick. Witkos also ' sought in an action in his own name to require Hardwick to indemnify him under G. L. c. 41, § 100, for medical bills incurred as a result of the aneurysm. The cases were consolidated for a bench trial on a “case stated” basis in which all of the evidence (which was entirely documentary) was stipulated. Hardwick now appeals from amended judgments entered against it in both actions.

Standard of review of a case stated. Where an action was treated as a case stated2 and the appellate court has all the documents, including the parties’ stipulation of the facts, that formed the basis for the judgment, “we decide the questions of law involved unaffected by [the trial judge’s] decision.” Tucci v. Di-Gregorio, 358 Mass. 493, 493-494 (1970). We thus review this case de nova. See Richardson v. Lee Realty Corp., 364 Mass. 632, 634 (1974) (“Because this appeal arises from a decision on a case stated, we deal with it anew, unaffected by any conclusions of law or inferences drawn by the [trial] judge”); Malonis v. Harrington, 442 Mass. 692, 696 (2004) (resolving the dispute on the case stated record); Pilch v. Ware, 8 Mass. App. Ct. 779, 780 (1979); Markell v. Sidney B. Pfeifer Foundation, Inc., 9 Mass. App. Ct. 412, 429 (1980); Hickey v. Green, 14 Mass. App. Ct. 671, 671 n.2 (1982). See also Nolan & Henry, Civil Practice § 33.7 (3d ed. 2004) (“It is now provided that upon a case stated by agreement of the parties for the decision of the court in any action, any court before which the case may come, either in the first instance or upon review, is at liberty to draw from the facts and documents stated in the case any inferences of fact which might have been drawn therefrom at a trial, unless the parties expressly agree that no inferences shall be drawn”).

Background. Witkos was both a full-time fire fighter for Ware and a part-time police officer for Hardwick. He had worked as a full-time fire fighter for Ware for many years. Witkos worked the entire day of August 29, 1996, at his Ware fire fighter job. *327Near the end of his shift, before leaving for his Hardwick police job, he felt weak, tired, and run down. After finishing his fire fighter shift, he was called to assist in a police action in Hard-wick that involved carrying contraband marijuana plants out of a field, over a stone wall, and onto a truck. He carried bundles of marijuana from the field to the truck three or four times. While performing this task, Witkos experienced disabling pain, collapsed, and was taken to a hospital where he was diagnosed with a dissecting aortic aneurysm. He incurred medical and hospital bills in the amount of $136,343.80 in connection with the treatment of the aneurysm.

Initially Ware began paying Witkos paid leave benefits under G. L. c. 41, § 111F.3 See Jones v. Wayland, 380 Mass. 110, 118 (1980). Ware subsequently terminated these payments, taking the position that they were made in error because his injury was sustained while working on his Hardwick job, not on his Ware job. As a result, Witkos filed a grievance under a collective bargaining agreement with Ware. Ware and Witkos entered into a written agreement in settlement of that grievance, pursuant to which Witkos released his claims against Ware and assigned to Ware his rights against Hardwick under G. L. c. 32, § 85H, and G. L. c. 41, § 111F.4 Witkos further received $19,278.73 in sick leave benefits from Ware and was allowed to keep the paid leave benefits (in the amount of $24,054.44) already received from Ware. The settlement agreement provided that Ware would keep amounts it recovered on the assigned claims, up to the total amount of the paid leave benefits and sick leave benefits it had paid to Witkos (i.e., $43,333.17). Any excess amounts recovered would belong to Witkos. Ware, to recoup its outlays, filed its action against Hardwick asserting Witkos’s assigned claims.5

Witkos was totally disabled by the aneurysm and never *328worked again on either job. As part of the settlement of the grievance, Ware also agreed not to oppose his application for accidental disability retirement benefits from the Hampshire County retirement board under G. L. c. 32, § 7.6 Witkos was successful in obtaining a disability retirement pension on October 22, 1997, at thirty-one years of age. That pension was granted from Hampshire County in connection with his full-time job as a Ware fire fighter under the so-called “heart law,” G. L. c. 32, § 94. 7 The heart law creates a presumption that a disability of a full-time fire fighter arising out of a heart condition is causally related to his job, without the need to prove further any such causal connection. See Blair v. Selectmen of Brookline, 24 Mass. App. Ct. 261, 265 (1987); Lisbon v. Contributory Retirement Appeal Board, 41 Mass. App. Ct. 246, 249 & n.5 (1996).

Meanwhile, Blue Cross Blue Shield of Massachusetts, which had paid for Witkos’s hospitalization and medical care expenses, retracted its coverage under the terms of its health insurance policy covering Witkos, on the ground that his injuries were work-related.8 Consequently Witkos became liable for these expenses, a liability for which he filed his action seeking indemnification from Hardwick under G. L. c. 41, § 100.

*329Benefits for a part-time police officer. A part-time police officer who is disabled while working on his part-time job and who is thereby unable to work at his “regular” job is entitled to statutory “injured on duty” benefits under G. L. c. 32, § 85H, the relevant provisions of which state:

“Whenever a call fire fighter or any member of a volunteer fire company in a town ... or reserve or special or intermittent police officer of a town, or a reserve police officer or reserve or call fire fighter of a city is disabled because of injury or incapacity sustained in the performance of his duty without fault of his own, and is thereby unable to perform the usual duties of his regular occupation at the time such injury or incapacity was incurred, he shall receive from the city or town for the period of such injury or incapacity the amount of compensation payable to a permanent member of the police . . . force thereof ... for the first year of service therein . . . provided, that no such compensation shall be payable for any period after such police officer . . . has been retired or pensioned in accordance with law . . . .”

G. L. c. 32, § 85H, as amended through St. 1970, c. 382, § 1.9 See Politano v. Selectmen of Nahant, 12 Mass. App. Ct. 738, 743 (1981). The “injured on duty” benefits paid to the part-time police officer under G. L. c. 32, § 85H, are designed to compensate the officer for the loss of income from a regular occupation. Politano v. Selectmen of Nahant, supra. The amount of these benefits, payable by the part-time employer, is equivalent to the amount of compensation that would be due to a first-year permanent member of the police department for the period of incapacity. This benefit ends upon retirement. See id. at 744.

It is not necessary to a temporary compensation claim under G. L. c. 32, § 85H, to establish that the disability “sustained in the performance of . . . duty” was caused specifically by the *330duty being performed. Cf. Wormstead v. Town Manager of Sau-gus, 366 Mass. 659, 662-663 (1975) (under G. L. c. 41, § 111F [which possesses operative language similar to that of G. L. c. 32, § 85H], proof that the injury specifically resulted from the work is not necessary). It is sufficient that the disabling condition arose without fault of the part-time employee while working on the part-time job. See G. L. c. 32, § 85H. Thus, under the unique circumstances of this case, it is of no consequence to this claim, contrary to the argument of Hard-wick, whether Witkos’s aneurysm may have been causally related in whole or in part to Ms job as a full-time Ware fire fighter.

Hardwick, citing Jones v. Wayland, 380 Mass, at 120, argues that Witkos should not be able to collect benefits for Ms Ware fire fighter job from both Ware (under G. L. c. 41, § 111F) and from Hardwick (under G. L. c. 32, § 85H). But unlike the situation in that case, tMs appeal does not involve the potential for overlapping benefits under § 85H and § 111F as related to an employee “who had lost only one job.” Jones v. Wayland, supra.10 Here Witkos would receive nothing more than he is entitled to under G. L. c. 32, § 85H, and will not be doubly compensated for Ms inability to work as a full-time Ware fire fighter. An amount equal to that wMch Ware has already paid to Mm (both m paid leave benefits and sick leave benefits) would be retained by Ware. Although any excess recovery (there is none here) would have gone to Witkos, there would be no more *331compensation to Witkos than the statute provides. This benefit is not limited by the amount he would have received on his primary job (so long as he had a primary job); it is measured by reference to what a full-time police officer in Hardwick earns. Compare Murphy v. Dover, 35 Mass. App. Ct. 904, 904-905 (1993) (a part-time call ambulance worker and police matron was not entitled to benefits, as her full-time work as a housewife was not considered a “regular occupation” because it did not constitute “a substantial source of income”).

Finally, there is no requirement, as argued by Hardwick, that Witkos or someone on his behalf make a formal claim for benefits under G. L. c. 32, § 85H, before commencing an action to enforce it. See Jones v. Wayland, 380 Mass. at 117.

Reimbursement for medical bills. We turn next to the claims of Witkos against Hardwick for indemnification for his medical bills under G. L. c. 41, § 100. This statute does require some causal connection between the medical condition treated and the performance of his job for Hardwick. See G. L. c. 41, § 100 (indemnification for reasonable medical expenses “incurred as the natural and proximate result of an accident occurring or of undergoing a hazard peculiar to his employment, while acting in the performance and within the scope of his duty without fault of his own”).11

Contrary to the arguments of Hardwick, there is evidence in the record to support Witkos’s claim of a causal connection between the acute dissection of his aortic aneurysm and his activity as a part-time police officer for Hardwick. Immediately *332before experiencing intense pain and collapsing, Witkos had been carrying bales of marijuana on his shoulder from a field, over a stone fence, and onto a truck. He made this trek three or four times in the course of approximately one-half hour. Additionally, a treating surgeon at Massachusetts General Hospital stated in a letter that “[tjhere is no question that the acute event of aortic dissection which was marked by the onset of very severe symptomatology occurred while at work and was related to the straining that he was doing at that time.” It is beyond dispute that this acute episode occurred while “acting in the performance and within the scope of his duty without fault of his own.” G. L. c. 41, § 100.

Witkos is not prevented, under the doctrine of issue preclusion, from claiming a causal connection between his police job and the disabling condition by the fact that he successfully obtained a disability pension from the Hampshire County board of retirement on the ground that he was disabled as a result of his Ware job as a fire fighter. This retirement outcome followed Ware’s agreement in the grievance settlement not to oppose Witkos’s application for disability retirement, which in effect allowed the causation presumption contained in the heart law, G. L. c. 32, § 94, to be conclusive.12 The causation question thus was not actually litigated, an indispensable prerequisite of the issue preclusion doctrine. See Kobrin v. Board of Registration in Medicine, 444 Mass. 837, 844 (2005).

Furthermore, the fact that such a condition may be causally related to Witkos’s job as a fire fighter does not preclude the possibility that it is also causally related to the performance of his job as a part-time police officer. A disability under the heart law is based on the presumption that heart disease is a long-term illness that can be exacerbated by the stress of working as a fire fighter. A final stressful incident which occurs while the fire fighter is working on some other job may be the immediate precipitating disabling event in a long chain of causation that *333included deterioration due to service as a fire fighter. In this sense the disability can logically and factually be related to both jobs.13

Nor is there any preclusive effect to the proceeding before the Hampshire County retirement board for accidental disability retirement benefits under the heart law and based upon the risk that Witkos might suffer another acute aortic episode in the future. Here Witkos sought indemnification for medical expenses under G. L. c: 41, § 100, for treatment relating to the acute event of aortic dissection that he suffered while on duty as a police officer. He is not prevented from making a claim for medical expenses.

There is support for the argument that Witkos made some application for these benefits. See G. L. c. 41, § 100. No particular form of application is required by statute. See ibid. The record shows that Witkos did enough to bring this claim to the attention of Hardwick to satisfy the statutory condition. Early in the process, Witkos discussed his medical bills with Hardwick’s police chief and Ware’s fire chief. The Ware fire chief had requested, on Witkos’s behalf, that Hardwick make arrangements to pay all the medical bills associated with his treatment. In addition, Witkos’s attorney submitted detailed medical bills to counsel for Hardwick. See O’Donovan v. Somerville, 41 Mass. App. Ct. at 917, 918 (1996) (employee forwarded his medical bills to the chief of the fire department).

We therefore agree with the trial judge’s conclusion that Wit-kos is entitled to indemnification from Hardwick for his relevant medical expenses.14

Conclusion. The stipulated facts and admissions in the pleadings show that (1) Witkos is disabled; (2) his incapacity was *334sustained while he was in the performance of his duties as a Hardwick special police officer, without his fault; and (3) as a result, he is unable to perform the usual duties of his regular occupation as a full-time fire fighter for the town of Ware. Both the amended judgment in the Ware action15 and the second amended judgment in Witkos’s action are affirmed.

So ordered.